Full mycology (2)

mycology

1. MEDICAL MYCOLOGY

Prepared by Lecturer Abdifitah Hassan Abdi Shoodhe Page 1

CHAPTER ONE
INTRODUCTION TO MICROBIOLOGY
Microbiology is a subject which deals with living organisms that are
individually too small to be seen with the naked eye.
It considers the microscopic forms of life and deals about their:
 Reproduction,
 physiology,
 participation in the process of nature,
 helpful and harmful relationship with other living things,
 Significance in science and industry.
Subdivision of microbiology
 Bacteriology deals about bacteria.
 Mycology deals about fungi.
 Virology deals about viruses.
 Phycology deals about algae
 Protozoology deals about protozoa
Characteristics of Microorganisms / Microbes
1) Typically unicellular
2) Too small to see with unaided eye
3) Located almost everywhere
4) Only a small % are pathogens
5) Most involved in environmental /ecosystem balance
Advantages of microorganisms
1) Decomposition (breakdown waste)
2) Nitrogen Fixation

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3) Foundation of food chain
4) Digestion in animals
5) Vitamin production
Disadvantages of microorganisms
1) They causes diseases in human, animals and plants
2) They causes food spoilage
The five kingdom system
The five kingdom system was first proposed in 1969
The five kingdoms include:
1) Plantae (the plants)
2) Fungi (the fungi)
3) Animalia (the animals)
4) Protista (the unicellular eukaryotes)
5) Monera (the prokaryotes)
Kingdom of Monera
Three categories: -
1. Eubacteria: Are our common, everyday bacteria, some of which
are disease causing; also the taxon from which mitochondria
originated.
2. Cyanobacteria: Are photosynthetic eubacteria, the taxon from
which chloroplast originated
3. Archaeobacteria: Are distinctive in their adaptation to extreme
environments (e.g., very hot, salty, or acidic) though not all
archaeobacteria live in extreme environments.

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These distinctions are more phenotypic than they are evolutionary
(i.e., a cyanobacteria is a eubacteria, and neither is an
archaebacteria).
Kingdom Protista
Protista like Monera consists mostly of unicellular organisms.
Distinctively, however, the members of Kingdom Protista are all
eukaryotic while the mebers of kingdom Monera are all prokaryotic.
Some members of protista are multicellular; however Kingdom
protista represents a grab bag, essentially the place where the
species are classified when they are not classified as fungi, animals
or plants.
Kingdom Fungi
Unlike protists, the eukaryotic fungi are typically non – aquatic
species.
They traditionally are nutrients absorbers plus have additional
distinctive features.
They do exist as unicellular fungi, which we called yeast or
multicellular fungi which we called molds.
The fungi are very simple plantlike structures that do not contain
chlorophyll. Thus, they cannot carry on photosynthesis and produce
their own food. They are saprophytes organisms which obtain their
nutrition from dead, decaying organic material. In a very real sense,
fungi are the scavengers of the microbes.

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Fungi may be unicellular like yeast or multicellular like molds.
Molds are filamentous, multicellular fungi often found on bread, cheese
and fruit, molds are of great importance to people, because they are
the major source of antibiotics
Both yeasts and molds have some harmful and some beneficial
members.
Yeasts are relatively large spherical or oval cells, visible under the low-
power magnification of the microscope. Mold filaments are visible to
the naked eye.
Yeasts are microscopic, single-celled members of the fungi division.
They are found on fruit and vegetable skins, on grain, and in water
and soil. The yeasts are spherical or oval shaped plant cells which lack
chlorophyll, because they cannot manufac ture their own food, they
depend upon other organic matter for nutrition.
If organisms depend upon nonliving organic matter for food they are
called saprophytes. Yeasts which live on the various sugars are usually
saprophytes.
If they depend upon living organisms for their food they are called
parasites. Candida albicans, yeast which invades the mucous
membranes of the mouth, throat and vagina is a parasite. It can cause
an ulcerative condition known as thrush.
The yeast cell reproduces by a process known as budding. Each cell
produces a cytoplasm protrusion, which is called a daughter cell. This
eventually breaks off from the mother cell and reproduces in the same

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manner. Like other plant cells yeasts have a cell wall, a cell
membrane, cytoplasm a nucleus, and a vacuoles.
Yeasts grow rapidly in a warm temperature and are killed at boiling
temperature. They can reproduce rapidly in a surgery solution. The
yeast sacharomyces cerevisiae causes the sugars to ferment into
alcohol and carbon dioxide, so yeasts en ables to make wine from
grape sugars cider from apple sugar, and beer from malt and hopes.
The carbon dioxide released by this process is also responsible for the
rising of dough in bread making.
Wild yeast found in the skin of fruits is called grape yeast. Yeast cakes
are referred to as bakers or brewer‟s yeast; they are used in the
making of bread and beer. Yeast is a rich source of vitamin B and
proteins.
Some of the activities of yeasts are harmful. These include the
spoilage of fruits, s and vegetables by fermentation, and the causing
of thrush and a few others diseases.
Molds are multicellular; filamentous fungi. Molds are the most familiar
of all the micro-organisms.
They are so common in our environment that anything exposed so the
air is likely to collect molds. Everyone is familiar with their
characteristic “moldy” odor
To the naked eye, molds can look like a fuzzy mass, a sooty black
area, or a tuft of cotton variously colored. Examined under the
microscope, however, molds are seen to be made up of long filaments
of protoplasm.

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Each individual of the threads is called a hypha
When is considered collectively, these hyphae are called a mycelium,
or plant body.
When the hyphae are ripe they form tiny knobs at their tips called
sporangia.
Each sporangium, when broken, releases thousands of microscopic
spores into the air.
These may subsequently start mold growths when they come in
contract with pieces of bread and other substances which can nourish
them.
This is how a mold reproduces. In addition, the spores also determine
the characteristic colors (white, blue-green, red, or brown) of the
different types of molds.
They mycelium grows like a mass of cobwebs. It sends short root like
branches into food. These branches secret enzymes which digest the
food, eventually the digested food is absorbed by the mold resulting in
the mold‟s growth. The part of the mycelium that grows on the food‟s
surface is the aerial mycelium. The aerial mycelium gives mold its
typically fuzzy appearance.
Molds require air, food, warmth, moisture and darkness in order to
thrive. To prevent the growth of a mold, the substance in question
must be deprived of one or more of these conditions.
For example, allowing direct sunlight to fall on an object will prevent
mold growth. When m olds attack materials which are not very

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nourishing, they remain stunted in their growth and are referred to as
mildew.
There are both harmful and useful molds. Harmful molds include those
which cause athlete‟s foot and food spoilage.
DOMAIN
The domain is a taxonomic category that, depending on point of view,
is either above the level of kingdom or overtakes the kingdom.
The domain system contains three members
1. Eukaryotes ( domain Eukarya )
2. Eubacteria ( domain Bacteria)
3. Archaebacteria ( domain Archaea)
Viral classification
Classification of viruses is not nearly as well developed as the
classification of cellular organisms.
Today viruses tend to be classified by their:
 Chemical,
 Morphological
 And physiological attributes (e.g. genome = DNA vs R NA, virion
particle = enveloped vs none enveloped).
Binomial nomenclature is not employed to name viruses; instead
viruses are named by their common names (e.g., Human
Immunodeficiency Virus a.k.a HIV)

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EUKARYOTIC CELL
Eu- true Karyote- nucleus
The eukaryotic cell has:
 a true membrane bound nucleus,
 usually containing multiple chromosomes,
 a mitotic apparatus,
 a well-defined endoplasmic reticulum
 And mitochondria.
PROKARYOTIC CELL
Pro- primitive Karyote- nucleus
The prokaryotic cell possesses naked DNA without associated basic
proteins, divides anatomically by binary fission and bounded by a semi
rigid cell wall.

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CHAPTER TWO
Introduction to Medical Mycology
The term "mycology" is derived from Greek word "mykes" meaning
mushroom.
Fungi are microorganisms in the domain eucarya, they show less
differentiation than plants, but a higher degree of organization than
the prokaryotes bacteria. The kingdom of the fungi (Mycota) comprises
over 50 000 different species, only about 200 of which have been
identified as human pathogens. Only about a dozen of these
“pathogenic” species cause 90% of all human mycoses. Many mycotic
infections are relatively harmless, for instance the dermatomycoses. In
recent years, however, the increasing numbers of patients with various
kinds of immune defects have resulted in more life -threatening
mycoses.
The taxonomy of the fungi is essentially based on their morphology. In
medical mycology, fungi are classified according to practical aspects as
dermatophytes, yeasts, molds, and dimorphic fungi. Molds grow in
filamentous structures, yeasts as single cells and dermatophytes cause
infections of the keratinized tissues (skin, hair, nails, etc.). Dimorphic
fungi can appear in both of the two forms, as yeast cells or as mycelia
(see the following pages).
Fungi are carbon heterotrophs. The saprobic or saprophytic fungi take
carbon compounds from dead organic material whereas biotrophic
fungi (parasites or symbionts) require living host organisms. Some
fungi can exist in both saprophytic and biotrophic forms.

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Definitions
Mycology--scientific discipline dealing with fungi
Mycologists--scientists who study fungi
Mycoses--diseases caused by fungi in human or animals
Mycotoxicosis: disease caused by fungal toxin in human or animals
Mykos = mycete = fungus
The ability of fungi to invade plant and animal tissue was observed in
early 19th century but the first documented animal infection by any
fungus was made by Bassi, who in 1835 studied the muscardine
disease of silkworm and proved the that the infection was caused by a
fungus Beauveria bassiana.
In 1910 Raymond Sabouraud published his book Les Teignes, which
was a comprehensive study of dermatophytic fungi.
He is also regarded as father of medical mycology.
Importance of fungi: Fungi inhabit almost every were in the
environment and humans are exposed to these organisms in various
fields of life.

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General properties of fungi:
They are eukaryotic; cells contain membrane bound cell organelles
including nuclei, mitochondria, golgi apparatus, endoplasmic reticulum,
lysosomes etc. They also exhibit mitosis.
Have ergosterols in their membranes and possesses 80S ribosomes.
Have a rigid cell wall and are therefore non -motile, a feature that
separates them from animals. All fu ngi possess cell wall made of
chitin.
Are chemoheterotrophs (require organic compounds for both carbon
and energy sources) and fungi lack chlorophyll and are therefore not
autotrophic.
Fungi are osmiotrophic; they obtain their nutrients by absorption.
They obtain nutrients as saprophytes (live off of decaying matter) or
as parasites (live off of living matter).
All fungi require water and oxygen and there are no obligate
anaerobes.
Typically reproduce asexually and/or sexually by producing spores.
They grow either reproductively by budding or non-reproductively by
hyphal tip elongation.
Food storage is generally in the form of lipids and glycogen.

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Advantages of fungi
1) They help in decomposition of dead animals and plants by
maintaining C, N cycles
2) Most of fungi produce antibiotics (penicillin + strep)
3) They are Edible (mushrooms)
4) They form Yeast (making bread and cheese)
5) Biosynthetic factories. The fermentation property is used for the
industrial production of alcohols, fats, citric, oxalic and gluconic
acids.
6) Model organisms for biochemical and genetic studies. Eg:
Neurospora crassa
7) Saccharomyces cerviciae is extensively used in recombinant DNA
technology, which includes the Hepatitis B Vaccine.
8) Yeasts provide nutritional supplements such as vitami ns and
cofactors.
9) Penicillium is used to flavour Roquefort and Camembert cheeses.
10) Ergot produced by Claviceps purpurea contains medically
important alkaloids that help in inducing uterine contractions.
11) Fungi (Leptolegnia caudate and Aphanomyces laevis) are
used to trap mosquito larvae in paddy fields and thus help in
malaria control.

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Disadvantages of fungi
1) They Rotten vegetables, damage crops & food stuff
2) They causes food poisoning (exotoxins)
3) They produce Other toxins (afla toxins)
 hepatotoxin and carcinogenic
4) They are mycotoxicosis =causes disease by toxic production
5) Fungal spores acts as allergens produce :-
 transient allergic reaction
 hay fever
 asthma like condition
 permanent lung disease
6) They cause animal diseases.
7) Toxins produced by poisonous mushrooms and within food
8) They cause Plant diseases.
9) They cause Spoilage of agriculture produce such as vegetables
and cereals

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Morphology of fungi
Hypha: this is the basic element of filamentous fungi with a branched,
tubular structure, 2–10 lm in width.
Mycelium: this is the web or matlike structure of hyphae. Substrate
mycelia (specialized for nutrition) penetrate into the nutrient
substrate, whereas aerial mycelia (for asexual propagation) develop
above the nutrient medium.
Fungal thallus: this is the entirety of the mycelia and is also called
the fungal body or colony.
Yeast: the basic element of the unicellular fungi. It is round to oval
and 3– 10 lmin diameter. Several elongated yeast cells chained
together and resembling true hyphae are called pseudohyphae.
Dimorphism: some fungal species can develop either the yeast or the
mycelium form depending on the environmenta l conditions, a property
called dimorphism. Dimorphic pathogenic fungi take the form of yeast
cells in the parasitic stage and appear as mycelia in the saprophytic
stage.

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Metabolism of fungi
All fungi are carbon heterotrophs, which mean they are dependent on
exogenous nutrient substrates as sources of organic carbon, and with
a few exceptions, fungi are obligate aerobes. Many species are capable
of maintaining metabolic activity in the most basic of nutrient
mediums. The known metabolic types of fungi include thermophilic,
psychrophilic, acidophilic, and halophilic species. The metabolic
capabilities of fungi are exploited in the food industry (e.g., in the
production of bread, wine, beer, cheese, or single-cell proteins) and in
the pharmaceutical industry (e.g., in the production of antibiotic
substances, enzymes, citric acid, etc.). The metabolic activity of fungi
can also be a damaging factor. Fungal infestation can destroy foods,
wooden structures, textiles, etc. Fungi also cause numerous plant
diseases, in particular diseases of crops.
Reproduction in Fungi
Asexual reproduction: This category includes the vegetative
propagation of hyphae and yeasts as well as vegetative fructification,
i.e., formation of asexual spores.
Hyphae elongate in a zone just short of the tip in which the cell wall is
particularly elastic. This apical growth process can also include
formation of swellings that develop into lateral hyphae, which can in
turn also branch out.
Yeasts reproduce by budding. This process begins with an outgrowth
on the mother cell wall that develops into a daugh ter cell or
blastoconidium. The isthmus between the two is finally cut off by

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formation of a septum. Some yeasts propagate in both the yeast and
hypha forms.
Vegetative fructification: A type of propagative form, the asexual
spores, is formed in this process. These structures show considerable
resistance to exogenous and help fungi spread in t he natural
environment. Asexual spores come in a number of morphological
types:
 conidia,
 sporangiospores,
 arthrospores, and
 blastospores.
These forms rarely develop during the parasitic stages in hosts, but
they are observed in cultures. The morphology of the asexual spores
of fungi is an important identification characteristic.
Sexual fructification: Sexual reproduction in fungi perfecti
(eumycetes) follows essentially the same patterns as in the h igher
eukaryotes. The nuclei of two haploid partners fuse to form a diploid
zygote. The diploid nucleus then undergoes meiosis to form the
haploid nuclei, finally resulting in the haploid sexual spores:
 zygospores,
 ascospores, and
 basidiospores.
Sexual spores are only rarely produced in the types of fungi that
parasitize human tissues.

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CHAPTER THREE
ECONOMIC SIGNIFICANCE OF FUNGI
Their activities as parasites:
(a) Fungi cause diseases to plants e.g. rusts and smuts.
Rusts are common on wild and cultivated plants, often causing severe
diseases. About 4,000 species are known. For example Puccinia,
granminis attacks grasses and cereals, but also grows on Berberis spp.
The fungus completes its life cycle on wheat and berberis and t his
makes the control of the fungus difficult.
Smuts are also parasites of cereals. The term smut refer to the mass
of dark powdery spores formed in sori on the leaves, stems or in the
flowers or fruits of the host plant.
There are 1,000 species that attac k Angiosperms. Examples are
Ustilago maydis (corn smut) both the rusts and smuts are very
important economically causing millions of dollars‟ worth of damage to
food crops. In addition to the damage done directly to plants, the
spores of smuts may also acc umulate in threshing machines
occasionally creating a smut dust that may explode violently to destroy
machines and grains by fire. The spores may also produce an allergic
effect on those working with the diseased grain.

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(b) Fungi cause diseases to man and animals:
There are approximately 1.5 million described species of fungi. A little
more than 400 of these species are known to cause disease in animals,
and far fewer of these species will specifically cause disease in people
The study of fungi as anima l and human pathogens is medical
mycology.
There is also veterinary mycology for animals, but the types of
diseases that are found in your pets often are the same as those that
are found in people.
The diseases of warm-blooded animals caused by fungi are known as
mycoses (sing.=mycosis). Although such diseases are relatively few,
the fungi that cause them have a wide host as well as geographical
range.
Most of these diseases are not fatal, but once contracted; they may
forever be a source of constant irritation and can lead to permanent
scaring, which is why they are not such a pretty sight to view. Fungous
infections are usually organized on the basis of the general body area
predominantly involved:
1. Superficial mycoses (infections)
Diseases of the skin, hair, nail and mucous membranes are the most
common of all fungal infections and have a worldwide distribution.
(a) Ringworm infections affect the keratinous tissues of hair, nail and
the horny layer (stratum corneum) of the skin. It is caused by closely
related fungi called dermatophytes e.g Epidermophyton floccosum ,

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Trichophyton spp., Microsporum spp. Which can colonize and digest
keratin, Examlpes are athlete‟s foot and ringworms on the scalp
(b) Yeast infections affect the skin, nail and mucous membranes of the
mouth (thrush) and vagina, and are usually caused by commensal
Candida species. Infection is usually endogenous in origin but genital
infection can be transmitted sexually.
2. Subcutaneous mycoses
Mycoses of the skin, subcutaneous tissues, fascia and bone, which
show slow localized spread They result from the traumatic inoculation
of saprophytic fungi from soil or decaying vegetation into the
subcutaneous tissue.
3. Systemic mycoses
Deep- seated fungal infections generally result from the inhalation of
air-borne spores produced by the fungi present as saprophytes in soil
and on plant material.
(a) Primary systemic diseases
Coccidioidomycosis caused by Coccidioides immitis, Histoplasmosis
caused by Histoplasma capsulatum
(b) Opportunistic systemic diseases
Aspergillosis caused by Aspergillus fumigatus and other Aspergillus
species.
Mucormycosis caused by Rhizopus, Absidia, Mucor and others.

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These infections are being seen with increasing frequency in patients
compromised by disease or drug treatment.
With an immune system that has been compromised, there has been a
rise in the number of people that have succumbed to fungal diseases.
In transplant patients, for example, these fungi are among the most
frequent causes of mortality due to infection.
People with weakened immune systems, such as people infected with
HIV and suffering from AIDS, can develop life -threatening fungal
diseases such as aspergillosis of the lungs. Symptoms resemble those
of tuberculosis. In these people, fungi can disseminate (spre ad
throughout the body), and infect major organs like the liver, spleen
and lungs.
Unlike bacterial diseases, fungal diseases are more difficult to treat.
Often topical and oral treatments are long term and may only be
partially successful in controlling the fungus, if they work at all. Many
serious bacterial diseases have been successfully treated and usually
without side effects from the drugs used. This usually is not the case
with treatment of fungal diseases.
Because bacteria are prokaryotes, the makeup of their cells is very
different from our own eukaryotic cells and pharmaceutical products,
such as antibiotics, can successfully destroy bacteria without harming
our cells, tissues and organs.
However fungi, like human cells, are eukaryotes, making the two types
of cells similar, at least more similar than to bacterial cells. There is

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enough similarity that when attempts are made to rid your body of a
fungal infection, with chemicals, it is difficult to find a treatment that
can remove the fungus selectively without doing significant damage to
your own cells.
(c) Some fungi are parasites to arthropods .
The fungal mycelium usually invades all body tissues and may
eventually cause suffocation by blocking the tracheal system.
Some fungal pathogens have a relatively broad host range (e.g
Beauveria bassiana, Metarhizium anisopliae, and Cordyceps spp.),
while others are more narrowly adapted to specific hosts like aphids
(e.g, Erynia redicans and Aschersonia spp.), muscoid flies (e.g,
Entomophthora muscae ), mosquito larvae (e.g., Lagenidium
giganteum,
Their activities as predators
Predatory fungi attack nematodes and other microorganisms using
remarkable array of trapping devices to attract, capture, kill and digest
nematodes for food.
Beneficial mutualistic relationships
(a) Mycorrhizae:
Mycorrhizae are symbiotic (mutalistic) associations that form between
the roots of most plant species and fungi.
These symbioses are characterized by bi -directional movement of
nutrients where carbon flows to the fungus and inorganic nutrients

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move to the plant, thereby providing a critical linkage between the
plant root and soil.
In infertile soils, nutrients taken up by the mycorrhizal fungi can lead
to improved plant growth and reproduction. As a result, mycorrhizal
plants are often more competitive and better able to tolerate
environmental stresses than are nonmycorrhizal plants. The partners
in this association are members of the fungus kingdom
(Basidiomycetes, Ascomycetes and Zygomycetes) and most vascular
plants. 90% of trees probably have them.
Their presence significantly increases the roots‟ effective absorptive
surface area and provides for a direct link between the process of
decomposition (which yields minerals) and absorption of these
minerals by plants. Mycorrhizae are beneficial both in nature and
agriculture.
Plants with them tend to grow better than those without them.
(b) Lichens
Lichens are mutualistic associations between fungi (usually an
ascomycete, few basidiomycetes or deuteromycetes) and algae
(usually a green alga or a Cyanobacterium). In the association the two
organisms are intertwined to form one thallus. The fungus component
of the lichen is called the mycobiont and the algal component is called
the phycobiont.
The fungus parasitizes the algal cells and also lives saprobically on the
algal cells that die. The alga survives under these conditions because
of it association with the fungal plectenchyma formed in the lichen

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thallus. The algal cells are protected from high light intensity, and the
fungus may also provide water and some nutrients that the alga
needs. A very delicate balance thus exists in the relationship that if
disturbed in favour of either, may result in disassociation and under
certain conditions, destruction of the less-favored organism.
Additional symbioses include:
(c) Those between fungus and insects.
The most interesting of the fungus-insect symbiotic relationships are
those involving colonial insects. One of the most important driving
forces that results in symbiotic relationships between microorganisms
is the inability of animals to digest cellulose. When you think of
herbivores, such as horses, sheep, cows, goats, etc., they do not
actually have the ability to digest the cellulose from the plant material
that they consume. Instead, they have symbiotic bacteria, in their
stomach, that have the cellulolytic enzymes that digest the plant
material for them. Other animals, do not carry microorganisms in their
gut, but rather consume mycelium in well decomposed plant material
as their food source. Thus, symbiotic relationships between animals
and various microorganisms are common.
Their activities as bio detergents
The metabolism of saprophytic fungi and bacteria decompose complex
organic molecules such as polysaccharides and proteins into simple
inorganic compounds such as carbon dioxide, nitrate and other
materials that plants can assimilate as raw materials for
photosynthesis. Fungal spores are so abundant in air that as soon as a

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leaf falls or an insect dies it is covered with fungal spores and is soon
infiltrated by saprophytic hyphae.
Fungi are among the only forms, which can break down lignin (a
polypeptide found in wood).
Unfortunately (for humans), fungi do not discriminate between
naturally occurring materials and natural resources being used by
humans.
Hence, a dead oak tree can be decomposed by fungi about as readily
as untreated wood in furniture, walls, floors, etc.
Consequently, undesired decomposition wreaks economic havoc with
humans‟ food and other products, including leather materials, e.g.
shoes, leather, and jackets. It should also be noted that fungi are very
tolerant to high osmotic pressure. Hence, they are able to colonize
habitats, which may be fairly unsuitable for other decomposers such as
bacteria.
Production of secondary poisonous metabolites called
mycotoxins.
Mycotoxins are poisonous chemical compounds produced by certain
fungi.
There are many such compounds, but only a few of them are regularly
found in food and animal feedstuffs such as grains and seeds .
Nevertheless, those that do occur in food have great significance in the
health of humans and livestock.

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Since they are produced by fungi, mycotoxins are associated with
diseased or mouldy crops, although the visible mould contamination
can be superficial.
The effects of some food-borne mycotoxins are acute, symptoms of
severe illness appearing very quickly.
Other mycotoxins occurring in food have longer term chronic or
cumulative effects of health, including the induction of cancers and
immune deficiency.
Information about food-borne mycotoxins is far from complete, but
enough is known to identify them as a serious problem in many parts
of the world, causing significant economic losses.
There are five mycotoxins, or groups of mycotoxins, that occur quite
often in food:
 deoxynivalenol/nivalenol;
 zearalenone;
 ochratoxin;
 fumonisins;
 and aflatoxins.
The food-borne mycotoxins likely to be of greatest significance for
human health in tropical developing countries are the fumonisins and
aflatoxins. Fumonisins were discovered as recently as 1988, so there is
little information on their toxicology.

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Losses Caused by Mycotoxicoses
 Outright food/feed losses
 Reduced productivity of livestock leads to less income from
animal products
 Lower foreign exchange earnings from reduced exports.
 Costs involved in shipment or trans -shipment, sampling,
analysis, etc. of exported goods that are subsequently refused
import entry; potential loss of overseas outlet.
 Fungal spores cause allergic (asthmatic) reactions to man
 Some mushrooms are poisonous and can kill within 24 hours e.g.
Amanita phalloides, Clitocybe dealbata.

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CHAPTER FOUR
IMPORTANCE OF FUNGI IN INDUSTRIES
Fungi are used in Industries for manufacturing large varieties of useful
materials for mankind such as Metabolites, enzymes and food.
The Filamentous fungi are used in many different processes in food
Industry for manufacture of different metabolites and variety of other
processes.
Uses of fungi
Fungi are used in many biotechnological applications.
(i) They cause fermentation and are therefore used in raising bread,
making cheese and tempee,(West Africa food) as well as alcohol
beverages.
(ii) Many saprophytic species are capable of synthesizing industrial
products, e.g. Rhizopus stolonifer (R. nigricans), the common bread
mould has been used commercially for the manufacture of cortisone.
Rhizopus oryzae is capable of producing considerable amount of
alcohol. Various species of Rhizopus e.g. R. sinensis, R. stolonifer, R.
oryzae and R. nodosus are also capable of forming large quantities of
lactic acid.
Other Mucorales also produce citric acid, succinic acid, oxalic acid and
other important hormones, enzymes and antibiotics.
Penicillin antibiotic is produced from Penicillium notatum and P.
chrysogenum. Antibiotic griseofulvin is produced by P. griseofulvum.

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Griseofulvin is the best antibiotic effective in the control of fungal skin
diseases (dermatomycoses) such as athletes‟ foot. Citric and gluconic
acids are manufactured commercially by the use of Aspergillus niger.
A niger can make citric acid from a sucrose solution by its enzymatic
activities.
Citric acid is used in the preparation of soft drinks.
Many other organic acids and various other chemicals are produced in
large or small quantities by members of this genus.
Enzyme preparations are made commercially through the use of these
fungi, and a number of antibiotics have been isolated from Aspergillus
cultures.
(iii) Some mushrooms have been used as a source of dyes e.g
indigotin-producing mushrooms Agari cus campestris, Morchella
rotunda, Schizophyllum commune.
Fungi are of excellent value nutritionally, and of great importance to
vegetarians.
Edible mushrooms are excellent sources of protein, have low -fat
content and are free of cholesterol. They are easily cultivable and are
consumed either in fresh or processed form. World -wide, the
production of cultivated edible mushrooms reaches now more than 4
million tons per year,
Yeasts and filamentous fungi secrete a plethora of important enzymes
in the growth medium together with other secondary metabolites.

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The fungi as food and feed are very nutritive since they contain
essential and nonessential amino acids.
Over recent years, consumption of fungal food had increased on a
global basis with rise in public concern about dietary and health issues.
Especially, those belonging to the vegetarian community have resorted
to eating either freshly cooked mushrooms or processed foods,
beverages and dietary supplements of fungal origin.
Fungi may be considered as FOE (ENEMY) or as FRIEND Examples for
the negative action of fungi are their activities in causing:
 Spoilage,
 Pathogen,
 Allergen,
 Toxin production.
On the other hand fungi may have a positive action, such as:
 Food and Fodder,
 Beverages,
 Medicine,
 Science
 Research, and Biological control
Three main uses
1. Alcohol production
2. Drug (Medicine) industries
3. Food Processing

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PRODUCTION OF ALCOHOL
Saccharomyces cerevisiae presence of excess glucose suppresses
respiration. In principle, materials rich in sugars (or starches) are then
fermented resulting in the production of alcohol.
Mainly three products
 Beer
 Wine
 Sake

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Production of wine
Species (used) Name
 Saccharomyces cerevisiae
 Saccharomyces carlsbergensis
 Saccharomyces uvarum
The yeast hydrolyses sugar, commonly sucrose, to pyruvic acid via the
EMP pathway, and then acetaldehyde to ethanol. The reaction is
exothermic, and unless the heat is dispersed, the reaction is slowed.
Further, though up to 50% of sugar can yield alcohol, by weight, the
solution rarely goes beyond 15% ethanol, because the fungus is
sensitive to high concentrations of ethanol.
PRODUCTION OF BEER
By using cereal grains, commonly barley, as the basis of fermentation
Grain is dried, and then germinated synchronously the germination
process involves release of amylases within the grain.
After various treatments, including addition of time, the liquid is
inoculated with specific yeasts and the mixture fermented for a short
period.
Production of sake
Organism Used - Aspergillus oryzae
Sake is a Japanese beverage made from rice. Steamed rice is
inoculated with Aspergillus oryzae to produce koji.

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Bread making
Bread consists of a mixture of flour (usually from cereals especially
wheat), with water, salt and sugar, leavened by yeast. Flour is mixed
with the remaining ingredients and incubated at about 25 C.
The yeast ferments the sugar forming carbon dioxide and alcohol. The
released gas causes bubbles to form by elastic extension of gluten (a
protein) in the flour.
Fungi in Biological Control of Pets
Fungi in the biological control of pests some fungi may be used to
suppress growth or eliminate harmful plant pathogens, such as
insects, mites, weeds, nematodes and other fungi that cause diseases
of important crop plants Some fungi attack insects and, therefore, can
be used as natural pesticides.
Fungi such as the Chinese caterpillar fungus, which parasitize insects,
can be extremely useful for controlling insect pests of crops. The
spores of the fungi are sprayed on the crop pests.
This method is generally cheaper and less damaging to the
environment than using chemical pesticides.

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FOOD PROCESSING
 Soya Sauce
 Blue Cheese
 Colours
 Flavours
Fungi may be the food, or may make the food edible follow
processing; Processing may make it possible to consume the foodstuff
by adding, modifying or removing components, including flavors,
nutritional elements such as vitamins or colors to enhance the appeal
of the food
Traditionally, mushrooms were identified and picked for food. The
mushrooms you see at the markets are now commercially cultivated.
These mushrooms are grown in highly controlled environments at
specific temperature and humidity levels. Examples of edible
mushrooms are Shiitake mushroom (Lentinus edodes ), Button
mushroom (Agaricus bisporus), Oyster mushroom ( Pleurotus ) Paddy
straw mushroom (Volvariella volvacea), Wood ear ( Auricularia
polytricha) silver ear (Tremella fuciformis) . Mushrooms are valuable
health food - low in calories, high in vegetable protein, iron, zinc,
chitin, fiber, vitamins and minerals. The usage of fungi for food,
preservation or other purposes by humans is wide-ranging and has a
rich history. For example, yeasts are used to ferment beer, wine and
bread. Fermentation: Is a chemical reaction in which a ferment
causes an organic molecule (primarily carbohydrates); to split into
simpler substances.

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Yeast + Glucose è Alcohol (Ethanol) + CO2
Three things are required for fermentation.
 First, fungi or bacteria must be present.
 Second, no oxygen must be present.
 Third, an organic compound must be present.
How fast fermentation occurs depends on temperature
Fungi have been used for thousands of years to modify foods and
beverages.
Bread made without yeast bread is flat. The addition of yeast to flat
bread dough causes the dough to rise during baking.
SOYA SAUCE
Fungi used
 Aspergillus oryzae
 Saccharomyces rouxii
BLUE CHEESE
Fungi used-
Penicillium roquefortii

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FUNGI IN DRUG INDUSTRY
At the beginning of the 21st century, Fungi were involved in the
industrial processing of more than 10 of the 20 most profitable
products used in medicine.
Two anti-cholesterol statins, the antibiotic penicillin and the
immunosuppressant cyclosporin A are among the top 10.
Each of these has a turnover in excess of $1 billion annually
HISTORY
Mushrooms have a long history of use in Chinese medicine to promote
good health and vitality and increasing the body‟s adaptive abilities.
Codyceps has been used in the treatment of:
 Cardiovascular diseases
 Liver diseases
 Respiratory diseases
 immune disorder
 sexual activity
 And other dysfunctions.
Shiitake mushroom is used as:
 anti-cholesterol
 cancer-reducing agent,
 And as an anti-Chronic Fatigue Syndrome agent.
Tremella fuciformis is used to:

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 cure tuberculosis
 high blood pressure
 And common cold.
The discovery of penicillin
The discovery of penicillin, one of the world‟s first antibiotics
Penicillium sp.
Scientific classification
Kingdom: Fungi
Phylum: Ascomycota
Class: Eurotiomycetes
Order: Eurotiales
Family: Trichocomaceae
Genus: Penicillium
Penicillin was discovered in London in September of 1928. As the
story goes, Dr. Alexander Fleming, the bacteriologist at St. Mary‟s
Hospital, returned from a summer vacation in Scotland.
Upon examining some colonies of Staphylococcus aureus, Dr.
Fleming noted that a mold called Penicillium notatum had
contaminated his Petri dishes. After carefully placing the dishes
under his microscope, he was amazed to find that the mold
prevented the normal growth of the staphylococci.
The area around the mold ring seemed to be free of bacteria.

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Fleming wondered: Is there something about this particular mold
which is killing off the bacteria?













As he continued to study the mold, Fleming realized that it was
from the genus "Penicillium," which had first been described in 1809
by Johann Heinrich . That name - penicillium - was selected
because the fungus, under a microscope, rese mbles a painter's
brush. The Latin word for "painter‟s brush" is penicillium.

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By 25 May 1940, Professor of Pathology - Dr Howard Florey and his
team had reached a point where they could carry out a new
experiment that would test whether penicillin could be an important
antibacterial drug. Eight mice were given lethal doses of
streptococci. Four of the mice were then given injections of
penicillin. By the next morning all the untreated mice were dead
while those that had received penicillin survived for days to weeks.
February 1941, Albert Alexander, a 43-year-old policeman, became
the first patient to be treated with penicillin.

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Antibiotics from fungi
Penicillin
Derived from Penicillium chrysogenum was first used successfully to
treat an infection caused by a bacterium.
The natural penicillin's have a number of disadvantages.
 They are destroyed in the acid stomach, and so cannot be
used orally.
 They also only act on gram positive bacteria.
Cephalosporin's
The original fungus found to produce the compounds was a
Cephalosporium, hence the name
Basidiomycetes, especially from tropical regions, produce an
enormous diversity of these compounds. Ex.Cefixime,Ceftriaxone
etc
Today, most antibiotics used in medicine are derived from bacteria.
Antibiotics produced by bacteria include streptomycin and
terramycin.
The only broadly useful antifungal agent from fungi is griseofulvin.
The original source was Penicillium griseofulvin.
Griseofulvin is fungi static, rather than fungicidal. It is used for the
treatment of dermatophytes, as it accumulates in the hair and skin
following topical application.

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Statins are products of metabolic reactions in fungi. Lovastatin
comes from Aspergillus terreus strains; mevastatin from Penicillium
citrinum. Statins inhibit an enzyme involved in the synthesis of
cholesterol and they‟ve become very important for control of
cholesterol levels in patients. Cholesterol is made in the liver, but
we also get it from our food. Diets high in fat result in a buildup of
cholesterol in the arteries and this can lead to heart attacks or
strokes.
Immune Suppressants
Cyclosporin A
It is a primary metabolite of several fungi, including Trichoderma
polysporum and Cylindrocarpon lucidum.
Cyclosporin A is a cyclic peptide consisting of 11 mainly hydrophobic
amino acids. It acts by inhibition of lymphocytes
The inhibition of T cells proliferation results in the suppression of
the activation process associated with invasion by foreign bodies.
Gliotoxins Belong to a class of compounds called Epi-poly-thiodioxo-
piperazines Produced by many fungi including Aspergillus fumigatus
Immune suppressants are essential for organ transplant patients.
The T cells of the human immune system recognize the new organ
as „foreign‟ and begin to destroy the organ. The filamentous fungus
called Tolypocladium inflatum was found to produce Cyclosporin A.
This drug prevents organ rejection by inhibiting T cell activation.

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Ergot Alkaloids
They act on the sympathetic nervous system resulting in the
inhibition of noradrenaline, causing dilation of blood vessels. They
also act directly on the smooth muscles of the uterus causing
contractions, thus their early use to induce abortion
Alkaloids are now produced in culture by strains of Calviceps
fusiformis and Calviceps paspalii.

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CHAPTER FIVE
General Aspects of Fungal Disease
Besides fungal allergies (e.g., extrinsic allergi c alveolitis) and
mycotoxicoses (aflatoxicosis), fungal infections are by far the most
frequent fungal diseases.
Mycoses are classified clinically as follows:
1) Primary mycoses (coccidioidomycosis, histoplasmosis,
blastomycoses).
2) Opportunistic mycoses (surface and deep yeast mycoses,
aspergillosis, mucormycoses, phaeohyphomycoses,
hyalohyphomycoses, cryptococcoses; penicilliosis,
pneumocystosis).
3) Subcutaneous mycoses (sporotrichos is, chromoblastomycosis,
Madura foot (mycetoma).
4) Cutaneous mycoses (pityriasis versicolor, dermatomycoses).
Little is known about fungal pathogenicity fac tors. The natural
resistance of the microorganism to fungal infection is based mainly on
effective phagocytosis whereas specific resistance is generally through
cellular immunity. Opportunistic mycoses develop mainly in pa tients
with immune deficiencies (e.g., in neutropenia). Laboratory diagnostic
methods for fungal infections mostly include microscopy and culturing,
in order to detect the pathogens directly, and identification of specific
antibodies. Therapeutics for treatment of mycoses include polyenes
(above all amphotericin B), azoles (e.g., itraconazole, fluconazole,
voriconazole), allylamines, antimetabolites (e.g., 5-fluorocytosine),

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and echinocandins (e.g., caspo fungin). Antimycotics are often
administered in combination.
Fungal Allergies and Fungal Toxicoses
Mycogenic Allergies
The spores of ubiquitous fungi continuously enter the respiratory tract
with air. These spores contain potent allergens to which susceptible
individuals may manifest strong hypersensitivity reactions. Depending
on the localization of the reaction, it may assume the form of allergic
rhinitis, bron- chial asthma, or allergic alveolitis. Many of these allergic
reactions are certified occupational diseases, i.e., “farmer‟s lung,”
“woodworker‟s lung,” and other types of extrinsic allergic alveolitis.
Mycotoxicoses
Some fungi produce mycotoxin s, the best known of which are the
aflatoxins produced by the Aspergillus species. These to xins are
ingested with the food stuffs on which the fungi have been growing.
Aflatoxin B1 may contribute to primary hepatic carcinoma, a disease
observed frequently in Africa and Southeast Asia.
Mycoses
Data on the general incidence of mycotic infections can only be
approximate, since there is no requirement that they be reported to
the health authorities.
It can be assumed that cutaneous mycoses are amo ng the most
frequent infections worldwide. Primary and opportunistic mycoses are,
on the other hand, relatively rare. Opportunistic mycoses have been

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on the increase in recent years and decades, reflecting the fact that
clinical manifestations are only observed in hosts whose immune
disposition allow them to develop.
Increasing numbers of patients with immune defects and a high
frequency of invasive and aggressive medical therapies are the factors
contributing to the increasing significance of mycoses.
Host-pathogen interactions
The factors that determine the onset, clinical picture, severity, and
outcome of a mycosis include interactions between fungal
pathogenicity factors and host immune defense mechanisms.
Compared with the situation in the field of bacteriology, it must be said
that we still know little about the underlying causes and mechanisms
of fungal pathogenicity. Human‟s show high levels of nonspecific
resistance to most fungi based on mechanical, humoral, and cellular
factors. Factors, phagocytosis by neutrophils granulocytes and
macrophages are the most important. Intensive contact with fungi
results in the acquisition of specific immunity, especially the cellular
type. The role of humoral immunity in specific immune defense is
secondary.
Diagnosis
The primary concern here is identification of the pathogen.
Microscopy: Native preparation: briefly heat material under coverslip
with 10% KOH.

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Stained preparation: stain with methylene blue, lactophenol blue,
periodic acid-Schiff (PAS), ink, etc.
Culturing: This is possible on universal and selective mediums.
Sabouraud dextrose agar can contain selective agents (e.g.,
chloramphenicol and cycloheximide), this medium has an acid pH of
5.6. The main identifying structures are morphological, in particular
the asexual a nd, if present, sexual reproductive structures.
Biochemical tests are used mainly to identify yeasts and are generally
not as important in mycology as they are in bacteriology.
Serology: By the identification of antibodies to special fungal antigens
in patient‟s serum. The Interpretation of serological findings is quite
difficult in fungal infections.
Antigen detection: By finding of specific antigens in the diagnostic
material by direct means using known antibodies, pos sible in some
fungal infections (e.g., cryptococcosis).
Cutaneous test: Cutaneous (allergy) tests with specific fungal
antigens can be useful in diagnosing a number of fungal infections.
Nucleic acid detection: Combined with amplification, such tests are
useful for rapid detection of mycotic diseases in immunocompromised
patients.

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Therapy (antifungal drugs)
A limited number of anti-infective agents are available for specific
treatment of fungal infections:
Polyenes:
These agents bind to membrane sterols and destroy the membrane
structure:
 Amphotericin B. Used In systemic mycoses. Fungicidal activity
with frequent side effects. There are conventional galenic form
and (new) various lipid forms.
 Nystatin, natamycin. Only for topical use in mucosal mycoses.
Azoles:
These agents disrupt ergosterol biosynthesis. Their effect is mainly
fungistatic with possible gastrointestinal side effects. Hepatic functional
parameters should be monitored during therapy:
 Ketoconazole. One of the first azoles. No longer used because of
side effects.
 Fluconazole. Oral or intravenous application. For the treatment of
surface and systemic mycoses and cryptococcal meningitis in
AIDS patients.
 Itraconazole. Oral and intravenous application, Use in systemic
and cutaneous mycoses and also for the treatment of
aspergillosis.
 Voriconazole. Oral and intravenous application. Good activity
against Candida and Aspergillus. No acitivity against Mucorales.

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Antimetabolites:
 5-Fluorocytosine; Interferes with DNA synthesis (base analog).
 Given by oral application in candidiasis , aspergillosis, and
cryptococcosis
 It is necessary to monitor the course of therapy for the
development of resistance.
 The toxicity of amphotericin B is reduced in combination with 5-
fluorocytosine.
Allylamines:
 Terbinafine: By oral and topical appli cation to treat
dermatomycoses.
 Inhibition of ergosterol biosynthesis
Echinocandins:
 Caspofungin has been a pproved as a salvage therapy in
refractory aspergillosis.
 It is useful also in oropharyngeal and esophageal candidiasis.
 Inhibition of the biosynthesis of glucan of the cell wall
Griseofulvin:
 This is an older antibiotic used in treatment of dermatomycoses.
 By oral application, therapy must often be continued for months.

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CHAPTER SIX
Fungi as Human Pathogens
Primary Mycoses
Primary systemic mycoses in clude histoplasmosis (Histoplasma
capsulatum), North American blastomycosis (Blastomyces
dermatitidis), coccidioidomycosis (Coccidioides immitis), and South
American blastomycosis (Paracoccidioides brasiliensis). The natural
habitat of these pathogens is the soil. Their spores are inhaled with
dust, get into the lungs, and cause a primary pulmonary mycosis.
Starting from foci in the lungs, the organisms can then be transported,
hematogenously or lymphogenously, to other organs including the
skin, where they cause granulomatous, purulent infection foci.
Laboratory diagnostics aim at direct detection of the pathogens under
the microscope and in cultures as well as identification of antibodies.
The therapeutics used to treat these infections are amphotericin B and
azoles. All of the primary systemic mycoses are endemic to certain
geographic areas, in some cases quite limited in extent. Central
Europe is not affected by these diseases. They are not communicable
among humans.
Histoplasma capsulatum (Histoplasmosis )
Histoplasma capsulatum is the pathogen responsible for
histoplasmosis, an intracellular mycosis of the reticuloendothelial
system. The sexual stage or form of this fungus is called Emmonsiella
capsulata.

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Morphology and culture:
H. capsulatum is a dimorphic fungus. As an infectious pathogen in
human tissues it always forms yeast cells (Fig. 6.1 ). The small
individual cells are often localized inside macrophages and have a
diameter of 2–3 lm.
Giemsa and gram staining do not “take” on the cellwalls of H.
capsulatum, for which reason the cells often appear to be surrounded
by an empty areola, which was incorrectly taken to be a capsule,
resulting in the designation H. capsulatum. This species can be grown
on the nutrient mediums normally used for fungal cultures. H.
capsulatum grows as a mycelium in two to three weeks on Sabouraud
agar at a temperature of 20–30 8C.

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Pathogenesis and clinical picture:
The natural habitat of H. capsulatum is the soil. Spores (conidia) are
inhaled into the respiratory tract, are taken up by alveolar
macrophages, and become yeast cells that reproduce by budding.
Small granulomatous inflammatory foci develop . The pathogens can
disseminate hematogenously from these primary infectio n foci. The
reticuloendothelial system (RES) is h it particularly hard.
Lymphadenopathies develop and the spleen and liver are affected.
Over 90% of infections remain clinically silent.
The clinical picture depends heavily on any predisposing host factors
and the infective dose. A histoplasmosis can also run its course as a
respiratory infection only. Disseminated histoplasmoses are also
observed in AIDS patients.
Diagnosis:
Suitable material for diagnostic analysis is provided by bronchial
secretion, urine, or scrapings from infection foci. For microscopic
examination, Giemsa orWright staining is applied and yeast cells are
looked for inside the macrophages and polymorphonuclear l eukocytes.
Cultures on blood or Sabouraud agar must be incubated for
severalweeks. Antibodies are detected using the complement fixation
test and agar gel precipitation. The diagnostic value of positive or
negative findings in a histoplasmin scratch test is doubtful.
Therapy:

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Treatment with amphotericin B is only indicated in severe infections,
especially the disseminated form.
Epidemiology and prevention:
Histoplasmosis is endemic to the Midwestern USA, Central and South
America, Indonesia, and Africa. With few exceptions, Western Europe
is free of the disease. The pathogen is not communicable among
humans. No special prophylactic measures are taken.
Coccidioides immitis (Coccidioidomycosis)
Morphology and culture:
C. immitis is an atypical dimorphic fungus. In cultures, this fungus
always grows in the mycelial form; in body tissues, however, it neither
buds nor producesmycelia. Wha t is found in vivo are spherical
structures (spherules) with thick walls and a diameter of 15 –60 lm,
each filled with up to 100 spherical-to-oval endospores.
C. immitis is readily cultivated on the usual fungus nutrient mediums.
After five days of incubation, a white, wooly (fuzzy) mycelial colony is
observed. One of the morphological characteristics of themycelium is
the asexual arthrospores seen as separate entities among the hyphae.
Pathogenesis and clinical picture:
The infection results from inhalation of dust containing arthrospores.
Primary coccidioidomycosis is always localized in the lungs, whereby
the level of manifestation varies from silent infections (60% of infected
persons) to severe pneumonia. Five percent of those infected develop
a chronic cavernous lung condition. In less than 1%, hematogenous

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dissemination produces granulomatous lesions in skin, bones, joints,
and meninges.
Diagnosis:
The available tools are pathogen detectio n in sputum, pus,
cerebrospinal fluid or biopsies, and antibody identification. The
spherules can be seen under the microscope in fresh material. The
fungus can be readily cultured on Sabouraud agar at 25 8C. The
resulting arthrospores are highly infectious and must be handled very
carefully. Antibodies can be detected using the complement fixation
test, gel precipitation or latex agglutination. A coccidioidin skin test
measuring any cellular allergy to components of the fungus is used as
an initial orientation test if an infection is suspected.
Therapy:
Amphotericin B can be used to treat the disseminated forms. An oral
azole derivative will serve as an alternative, or for use, in clinically less
severe forms.
Epidemiology and prevention:
Coccidioidomycosis is endemic to desert areas of California, Arizona,
Texas, New Mexico, and Utah and is only rarely observed elsewhere.
The source of infection is the fungus-rich soil. Animals can also be
infected. This disease is not transmitted among humans or from
animals to humans.

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Blastomyces dermatitidis (North American Blastomyc osis)
Blastomyces dermatitidis is a dimorphic fungus that causes a chronic
granulomatous infection. The pathogens occur naturally in the soil and
are transmitted to humans by inhalation.
The primary blastomycosis infection is pulmonary. Secondary
hematogenous spread can lead to involvement of other organs
including the skin.
Laboratory diagnostic methods include microscopy and culturing to
identify the fungus in sputum, skin lesion pus, or biopsy material.
Antibody detection using the complement fixation te st or agar gel
precipitation is of limited diagnostic value. Amphotericin B is the
therapeutic agent of choice. Untreated blastomycoses almost always
have a lethal outcome.
Infections are also relatively frequent in animals, especially dogs.
Susceptible persons cannot, however, be infected by infected animals
or humans. There are no prophylactic measures.
Paracoccidioides brasiliensis (South American Blastomycosis)
Paracoccidioides brasiliensis (syn. Blastomyces brasiliensis) is a
dimorphic fungus that, in living tissues, produces thick-walled yeast
cells of 10–30 lm in diameter, most of which have several buds. When
cultivated (25 8C), the fungus grows in the mycelial form.
The natural habitat of P. brasiliensis is probably the soil. Human
infections are caused by inhalation of spore -laden dust. Primary
purulent and/or granulomatous infection foci are found in the lung.

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Starting from these foci, the fungus can disseminate hematogenously
or lymphogenously into the skin, mucosa, or lymphoid organs. A
disseminated paracoccidioidomycosis progresses gradually and ends
lethally unless treated. The therapeutic agents of choice are azole
derivatives (e.g., itraconazole), amphotericin B, and sulfonamides.
Therapy can prevent the disease from progressing, although no c ases
are known in which the disease is eliminated over the longer term.
Laboratory diagnostics are based on detection of the pathogen under
the microscope and in cultures as well as on antibody detection with
the complement fixation test or gel precipitation.
Paracoccidioidomycosis is observed mainly among farmers in rural
parts of South America.

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CHAPTER SEVEN
Opportunistic Mycoses (OM)
Opportunistic mycoses (OM) that affect skin and mucosa as well as
internal organs are caused by both yeast and molds. A precondition for
development of such infections is a pronounced weakness in the host‟s
immune defenses.
Candidiasis is an endogenous infection. Oth er OMs are exogenous
infections caused by fungi that naturally inhabit the soil or plants.
These environmental fungi usually invade via the respiratory tract. The
most important are aspergillosis, cryptococcosis, and the
mucormycoses. Besides Candida and other yeasts,
phaeohyphomycetes a nd hyalohyphomycetes, which are only very
mildly pathogenic, can also cause systemic infections. All OMs have a
primary infection focus, usually in the upper or lower respiratory tract.
From this focus, the pathogens can disseminate hemat ogenously
and/or lymphogenously to infect additional organs. Infection foci
should be removed surgically if feasible. Antimycotic agents are used
in chemotherapy. In infected
immunocompromised patients, the prognosis is usually poor.
Candida (Sore) (Candidiasis):
Candidiasis is a fungal infection caused by yeasts that belong to the
genus Candida. There are over 20 species of Candida yeasts that can
cause infection in humans, the most common of which is Candida
albicans. Candida yeasts normally live on the skin and mucous

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membranes without causing infection; however, overgrowth of these
organisms can cause symptoms to develop. Symptoms of candidiasis
vary depending on the area of the body that is infected.
Candidiasis that develops in the mouth or throat is called “thrush” or
oropharyngeal candidiasis.
Candidiasis in the vagina is commonly referred “yeast infection.”
Invasive candidiasis occurs when Candida species enter the
bloodstream and spread throughout the body.
 If it is in the mouth or throat, it is called oral candidiasis,
oropharyngeal candidiasis, or thrush.
 If it affects the genital area, it is called a yeast infection. In
women, it may be called a vulvovaginal yeast infection.
 If yeast infects the skin on a baby's bottom area, it causes a
diaper rash.
 If the infection enters your bloodstream, it is called invasive
candidiasis or candidemia.
 Symptoms and treatment depend on which part of the body is
infected.
At least 70% of all human Candida infections are caused by C.
albicans, the rest by C. parapsilosis, C. tropicalis, C. guillermondii, C.
kruzei, and a few other rare Candida species.

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Morphology and cu lture:
Gram staining of primary preparations reveals C. albicans to be Gram-
positive, budding, oval yeast with a diameter of approximately 5 lm.
Gram-positive pseudohyphae are observed frequently and septate
mycelia occasionally.
C. albicans can be grown on the usual culture mediums. After 48 hours
of incubation on agar mediums, round, whitish, s omewhat rough-
surfaced colonies form. They are differentiated from other yeasts
based on morphological and biochemical characteristics.

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Pathogenesis and clinical pictures:
Candida is a normal inhabitant of human and animal mucosa
(commensal). Candida infections must therefore be considered
endogenous. Candodoses usually de velop in persons whose immunity
is compromised, most frequently in the presence of disturbed cellular
immunity. The mucosa is affected most often, less frequently the outer
skin and inner organs (deep candidiasis).
Oral Candidiasis: is superficial infection of the oral mucosa & tongue,
caused by Candida albicans, mostly endogenous.
May spread to the pharynx or oesophagus
Common in:
 Infants & elderly.
 In immunocompromised: AIDS.
 Malnourished children ( bottle fed)
 Patients on prolong antibiotics.
Female genitalia: vulvo-vaginitis (vaginal Thrush) inflammation of
the vulva &vagina.
Associated with:
 severe Itching
 pain
 vaginal discharge
 white – thick

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 odorless
Usually there is no predisposing factors of vaginal Thrush
Common in:
 pregnancy
 diabetics
 Females using oral contraceptive pills with high estrogen
level.
Predisposing factors of candidiasis:
 Diabetes,
 pregnancy,
 progesterone therapy,
 And intensive antibiotic treatment that eliminate the normal
bacterial flora.
Skin is mainly infected on the moist, warm parts of the body. Candida
can spread to cause secondary infections of the lungs, kidneys, and
other organs. Candidial endocarditis and endophthalmitis are observed
in drug addicts. Chronic mucocutaneous candidiasis is observed as a
sequel to damage of the cellular immune system.
Diagnosis:
This involves microscopic examination of preparations of different
materials, both native and Gram -stained. Candida grows on many
standard nutrient mediums, particularly well on Saboura ud agar.
Typical yeast colonies are identified under the microscope and based
on specific metabolic evidence.

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Detection of Candida-specific antigens in serum (e.g., free mannan) is
possible using an agglutination reaction with latex particles to which
monoclonal antibodies are bound. Various methods are used to identify
antibodies in deep candidiasis (agglutination, gel precipi tation,
enzymatic immunoassays, immunoelectrophoresis).
Therapy:
Nystatin and azoles can be used in topical therapy. In cases of deep
candidiasis, amphotericin B is still the agen t of choice, often
administered together with 5-fluorocytosine. Echinocandins (e.g.,
caspofungin) can be used in severe oropharyngeal and esophageal
candidiasis.
Epidemiology and prevention:
Candida infections are, with the exception of candidiasis in newborn
children, endogenous infections.

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CHAPTER EIGHT
Aspergillus (Aspergillosis):
Aspergillosis is a spectrum of diseases of humans and animals caused
by members of the genus Aspergillus.
 Aspergilloses are group of mycosis caused by different species of
the genus Aspergillus
 Aspergilloses are most frequently caused by Aspergillus
fumigatus and A. flavus.
 Aspergillus niger, A. nidulans, and A. terreus are found less
often.
 Aspergilli are ubiquitous in nature.
 They are found in large numbers on rotting plants.
 The type of disease and severity depends upon the physiologic
state of the host and the species of Aspergillus involved.
These include:
(1) mycotoxicosis due to ingestion of contaminated foods;
(2) Allergy and sequelae to the presence of conidia or transient growth
of the organism in body holes
(3) Colonization without extension in preformed cavities and
debilitated tissues fatal disseminated disease.
(4) Invasive, inflammatory, granulomatous, necrotizing disease of
lungs, and other organs; and rarely
(5) Systemic

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Morphology and culture:
Aspergillus is recognized in tissue preparations, sputum by the
filamentous, septate hyphae, which are approximately 3–4 lm wide
with Y-shaped branchings
Aspergillus grows rapidly, inmycelial form, on many of the mediums
commonly used in clinical microbiology. Sabouraud agar is suitable for
selective culturing.
Pathogenesis and clinical pictures:
The main portal of entry for this pathogen is the bronchial system, but
the organism can also invade the body through injuries in the skin or
mucosa.
The following localizations are known for aspergilloses:
Aspergillosis of the respiratory tract:
An aspergilloma is a circumscribed “fungus ball” that usually grows in
a certain space (e.g., a cavern). Another pulmonary aspergillosis is a
chronic, necrotizing pneumonia. Acute, invasive pulmonary
aspergillosis is seen in patients suffering from neutropenia or AIDS or
following organ transplants and has a poor prognosis. Another
aspergillosis of the respiratory tract is tracheobronchitis. Of all fungi,
aspergilli are most frequently responsible for various forms of sinusitis.
In persons with atopic allergies, asthma may be caused by an allergic
aspergillus alveolitis.

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Other aspergilloses:
Endophthalmitis can develop two to three weeks after surge ry or an
eye injury and the usual outcome is loss of the eye. Cerebral
aspergillosis develops after hematogenous dissemination. Less often,
Aspergillus spp. causes endocarditis, myocarditis, and osteomyelitis.

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Diagnosis:
Since Aspergillus is a frequent contaminant of diagnostic materials,
diagnosis based on direct pathogen detection is difficult.
Finding the typically branched hyphae in the primary preparation a nd
repeated culture growth of Aspergillus make the diagnosis probable
If the branched hyphae are found in tissue biopsies stained with
methenamine silver stain, the diagnosis can be considered confirmed.
Using latex particles coated with monoclonal antibodies, Aspergillus-
specific antigen (Aspergillus galactomannan) can be detected in blood
serum in an agglutination reaction. Antibodies in systemic
aspergilloses are best detected by immunodiffusion and ELISA. PCR -
based methods detect Aspergillus- DNA.
Therapy:
High-dose amphotericin B, administered in time, is the agent of choice.
Azoles can also be used. The echinocandi n caspofungin has been
approved in the treatment of refractory aspergillos is as salvage
therapy. Surgical removal of local infection foci (e.g., aspergilloma) is
appropriate.

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Cryptococcus neoformans (Cryptococcosis)
Morphology and culture:
C. neoformans is encapsulated yeast. The individual cell has a
diameter of 3–5 lm and is surrounded by a polysaccharide capsule
several micrometers wide.
C. neoformans can be cultured on Sabouraud agar at 30 –35 8C with
an incubation period of three to four days.
Pathogenesis and clinical picture:
The normal habitat of this pathogen is soil rich in organic substances.
The fungus is very frequently found in bird droppings.
The portal of entry in humans is the respiratory tract. The organisms
are inhaled and enter the lungs, resulting in a pulmonary
cryptococcosis that usually runs an inapparent clinical course. From
the primary pulmonary foci, the pathogens spread hematogenously to
other organs, above all into the central nervous system (CNS), for
which compartment C. neoformans shows a pronounced affinity. A
dangerous meningoencephalitis is the result. Gosod preconditions for
dissemination from the lung foci are provided especially by primary
diseases that weaken the immune defenses. Malignanci es and steroid
therapy are other frequent predisposing factors. AIDS patients also
frequently develop cryptococcoses.

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Diagnosis:
This is particularly important in meningitis. The pathogens can be
detected in cerebrospinal fluid sediment usin g phase contrast

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microscopy. An ink preparation results in a negative image of the
capsule. Culturing is most successful on Sabouraud agar. C.
neoformans can be differentiated from other yeasts and identified
based on special metabolic properties (e.g., breakdown of urea). A
latex agglutination test is available for detection of capsule
polysaccharide in cerebrospina l fluid and serum (anticapsular
antibodies coupled to latex particles). Identification of antibodies to
the capsular polysaccharide is achieved by means of an agglutination
test or an enzymatic immunosorbence test.
Therapy:
Amphotericin B is the agent of choice in CNS cryptococcosis, oftenused
in combination with 5-fluorocytosine.
Epidemiology and prevention:
No precise figures are available on the frequen cy of pulmonary
cryptococcosis. The incidence of the attendant meningoencephalitis is
one case per million inhabitants per year. There are no specific
prophylactic measures.

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CHAPTER NINE
Mucor, Absidia, Rhizopus (Mucormycoses)
Mucormycoses are cause d mainly by various species in the genera
Mucor, Absidia, and Rhizopus. More rarely, this type of opportunistic
mycosis is caused by species in the genera Cunninghamella,
Rhizomucor, and others. All of these fungal genera are in the order
Mucorales and occur ubiquitously. They are found especially often on
disintegrating organic plant materials.
Morphology and culture:
Mucorales are molds that produce broad, nonseptate hyphae with thick
walls that branch off nearly at right angles.
Mucorales are readily cultured. They grow on all standard mediums,
forming high, and whitish-gray to brown, “fuzzy” aerial mycelium.
Culturing is best done on Sabouraud agar.
Pathogenesis and clinical pictures:
Mucorales are typical opportunists that only cause infections in
patients with immune deficiencies or metabolic dis- orders (diabetes).
The pathogens penetrate into the target organic system with dust.
They show a high affinity to vascular struc tures, in which they
reproduce, potentially resulting in thrombosis and infarction.

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The infections are classified as follows acc ording to their
manifestations:
Rhinocerebral mucormycosis : spreads from the nose or sinuses and
may affect the brain. Most often observed as a sequel to diabetic
acidosis.
Pulmonary mucormycosis : with septic pulmonary infarctions.
Occurs most frequently in neutropenic malignancy p atients under
remission therapy
Gastrointestinal mucormycosis (vary rare): seen in
undernourished children and accompanied by infarctions of the
gastrointestinal tract.
Cutaneous mucormycosis : manifests as a sequel to skin injuries,
especially burns.
Disseminated mucormycosis : as a sequel to any of these forms,
especially pulmonary mucormycosis.

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Diagnosis:
Confirmation of diagnosis is based on detection of tissue infiltration by
morphologically typical fungal hyphae. Culturing can be attempted on
Sabouraud agar. Identification concerns solely th e morphological
characteristics of the fructification organs. There is no method of
antibody-based diagnosis.
Therapy:
Amphotericin B is the antimycotic agent of choice. Surgical measures
as required Control of the primary disease.

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Phaeohyphomycetes, Hyalohyphomycetes,Opportunistic
Yeasts, Penicillium marneffei
The list of clinically relevant fungi previously not categorized as classic
opportunists has lengthened appreciably in re cent years. These
organisms are now being found in pathogenic roles in patients with
malignancies, in AIDS patients, in patients undergoing cytostatic and
immunosuppressive therapies, massive corticosteroid therapy, or long-
term treatment with broadspectrum antibiotics. The terms
phaeohyphomycetes, hyalohyphomyce tes, and opportunistic yeasts
have been created with the aim of simplifying the nomenclature.
Phaeohyphomycoses
These are subcutaneous and paranasal sinus infections caused by
“dematious” molds or “black fungi.” To date, numerous genera and
species have been described as pathogenic agents. Common to all is
the formation of hyphae, which appear as a brownish black color due
to integration of melanin in the hyphal walls. Examples of the genera
include Curvularia, Bipolaris, Exserohilum, Wangiella, Dactylaria,
Ramichloridium, Chaetomium , and Alternaria. The natural habitat of
these fungi is the soil, they occur worldwide.
Phaeohyphomycetes invade the body through injuries in the skin or
inhalation of spores. Starting from primary foci (see above), the
pathogens can disseminate hematogenously to affect other organs
including the CNS.

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The clinical pictures of such infections most closely resemble the
mucormycoses and aspergillosis. If feasible, surgical removal of
infected tissues and
administration of antimycotic agents is indicated. The prognosis is
poor.
Hyalohyphomycoses:
This collective term is used formycoses caused by hyaline (melanin-
free) molds. Examples of s ome of the genera are Fusarium ,
Scopulariopsis, Paecilomyces, Trichoderma, Acremonium, and
Scedosporium.
These fungi are also found all over the world. Pathogenesis, clinical
pictures, therapy, and prognosis are the same as for the
phaeohyphomycoses.
Opportunistic yeast mycoses:
Other yeasts besides the most frequent genus by far, Candida, are
also capable of causing mycoses in immunosuppressed patients. They
include Torulopsis glabrata, Trichosporon beigelii, and species of the
genera Rhodotorula, Malassez ia, Saccharomyces, Hansenula, and
others.
These “new”mycoses are not endogenous, but rather exogenous
infections. In clinical and therapeutic terms, they are the same as
candidiasis. Malassezia furfur occasionally causes catheter sepsis in
premature neonates and persons who have to be fed lipids
parenterally. Lipids encourage growth of this yeast.

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Penicilliosis:
This fungal infection is caused by the dimorphic fungus Penicillium
marneffei, which probably inhabits the soil. P. marneffei infections are
one of the most opportunistic infections most frequently seen in AIDS
patients who either live in Southeast Asia or have stayed in that area
for a while.
The infection foci are located primarily in the lungs, from where
dissemination to other organs can take pl ace. The therapeutic of
choice in the acute phase is amphotericin B, this treatment must be
followed by long-term prophylactic azoles (itraconazole) to prevent
remission.
Pneumocystis carinii (Pneumocystosis)
Pneumocystis carinii is a single-celled, eukaryotic microorganism that
was originally classified as a protozoan, but is now considered a
fungus. This pathogen can cause pneumonia in persons with defective
cellular immune systems, in particular those showing AIDS.
Extrapulmonary manifestations are also recorded in a small number of
cases. Laboratory diagnostic methods include direct detection of the
microbes under the microscope, by means of direct
immunofluorescence or PCR. Appropriate anti -infective agents for
therapy include cotrimoxazole, pentamidine, or a combination of the
two.
Pneumocystis carinii is a single-celled, eukaryotic microorganism that
was, until recently, classified with the protozoans. Molecular DNA
analysis has revealed that it resembles fungi more than it do es

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protozoans, although some of the characteristic properties of fungi,
such as membrane ergoster ol, are missing in Pneumocystis carinii.
This microbe occurs in the lungs of many mammalian species including
humans without causing disease in the carriers.
Clinically manifest infections emerge in th e presence of severe
underlying defects in cellular immunity, as in AIDS.
Morphology and developmental cycle:
Three developmental stages are known for P. carinii. The trophozoites
are elliptical cells with a diameter of 1.5–5 lm. Presumably, the trophic
form reproduces by means of binary transverse fission, i.e., asexually.
Sexual reproduction does not begin until two haploid trophozoites fuse
to make one diploid sporozoite (or precyst), which are considered to
be an intermediate stage in sexual reproduction.
After further nuclear divisions, the sporozoites possess eight nuclei at
the end of their development. The nuclei then compartmentalize to
form eight spores with a diameter of 1–2 lm each, resulting in the
third stage of devel- opment, the cyst. The cysts then release the
spores, which in turn develop into trophozoites.
Culture:
P. carinii cannot be grown in nutrient mediums. It can go through a
maximum of 10 developmental cycles in cell c ultures. Sufficient
propagation is only possible in experimental animals, e.g., rats. This
makes it difficult to study the pathogen‟s biology and the pathogen ic
process and explains why all aspects of these infections have not yet
been clarified.

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Pathogenesis and clinical pictures:
Humans show considerable resistance to P. carinii infections, which
explains why about two-thirds of the populace are either carriers or
have a history of contact with the organism. Disease only becomes
manifest in the presence of defects in the cellular immune system.
Of primary concern among the clinical manifestations is the interstitial
pneumonia. Profuse proliferation of the pathogen in the alveoli
damages the alveolar epithelium. The pathogens then penetrate into
the interstitium, where they cause the pneumonia. Startin g from the
primary infection foci, the fungi spread to other organs in 1–2% of
cases, causing extrapulmonary P. carinii infections (of the middle ear,
eye, CNS, liver, pancreas, etc.)
Diagnosis:
Suitable types of diagnostic material include pulmonary biopsies or
bronchoalveolar lavage (BAL) specimens from the affected lung
segments.
Therapy:
Acute pneumocystosis is treated with cot rimoxazole (oral or
parenteral) or pentamidine (parenteral) or a combination of both of
these anti-infective agents. Pentamidine can also be applied in aerosol
form to reduce the side effects.

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CHAPTER TEEN
SUPERFICICAL MYCOSIS (Cutaneous Mycoses)
Superficial Mycoses are fungal infection, affecting the surface areas of
the skin are caused by a variety of fungi.
Superficial mycoses are the infections affecting the external parts of
the body like skin, nails and hair, by different kinds of Tinea or
ringworm.
These organisms are particular saprophytes, capable of digesting the
fibrous proteins like keratin.
The fungi are called dermatophytes (which means skin plants)
Dermatophytes, or more properly, keratinophilic fungi, produce
extracellular enzymes (keratinases) which are capable of hydrolyzing
keratin.
What Is Ringworm (Dermatophytosis)?
Dermatophytosis, more commonly known as ringworm, is a fungal
infection of the skin.
Ringworm infection can affect both humans and animals.
The infection initially presents itself with red patches on affected areas
of the skin and later spreads to other parts of the body.
The infection may affect the skin of the scalp, feet, groin, beard, or
other areas.

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What Causes Ringworm (Dermatophytosis)?
Three different types of fungi can cause this infection. They are called
trichophyton, microsporum, and epidermophyton.
It‟s possible that these fungi may live for an extended period as spores
in soil.
Humans and animals can contract ringworm after direct contact with
this soil.
The infection can also spread through contact with infected animals or
humans.
The infection is commonly spread among children and by sharing items
that may not be clean.

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Tinea means "ringworm". Dermatologists use this term to refer to a
variety of lesions of the skin or scalp.
 Tinea unguium (onychomycosis)
 Tinea capitis
 Tinea corporis
 Tinea pedis - "athlete's foot“
 Tinea cruris
 Tinea barbae
 Tinea versicolor
1. Tinea unguium
Tinea unguium: The most common fungus infection of the nails, also
called onychomycosis.
Onychomycosis makes the nails look white.
Those at increased risk for developing onychomycosis include:
People with diabetes;
People with disease of the small blood vessels (peripheral vascular
disease);
Older women (perhaps because estrogen deficiency increases the risk
of infection); Women of any age who wear artificial nails (acrylic or
"wraps")
Artificial nails increase the risk for onychomycosis because, when an
artificial nail is applied, the nail surface is usually abraded with an
emery board damaging it, emery boards can carry infection, and water

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can collect under the artificial nail creating a moist, warm environment
favorable for fungal growth.

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2 Tinea capitis
Tinea capitis is a fungal infection of the scalp. It is also
called ringworm of the scalp.
Tinea capitis is caused by mold –like fungi called (dermatophytes).
Tinea capitis most often affect children and goes away at puberty and
it can occur at any age without hygienic.
It can transmit by either (Direct or Indirect)
Causes:
Fungi are germs that can live on the dead tissue of the hair, nails, and
outer skin layers. Tinea capitis is caused by mold -like fungi called
dermatophytes.
Risk factors:-
The fungi grow well in warm, moist areas. A tinea infection is more
likely if you:
Have minor skin or scalp injuries
Do not bathe or wash your hair often
Have wet skin for a long time (such as from sweating)
Tinea capitis or ringworm can spread easily. It most often affects
children and goes away at puberty. However, it can occur at any age.
You can catch tinea capitis if you come into direct contact with an area
of ringworm on someone else's body. You can also get it if you touch

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items such as clothing that have been used by someone with
ringworm. The infection can also be spread by pets, particularly cats.







3. Tinea corporis
Tinea corporis is a skin infection due to fungi. It is also
called ringworm of the body.
Related skin fungus infections may be found:
 On the scalp
 In a man's beard
 In the groin (jock itch)
 Between the toes
 Other places on the skin
Causes:
Tinea corporis is caused by mold-like fungi called dermatophytes.
Tinea corporis is common in children but can occur in people of all

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ages. Fungi do well in warm, moist areas. A tinea infection is more
likely if you:
 Have wet skin for a long time (such as from sweating)
 Have minor skin and nail injuries
 Do not bathe or wash your hair often
 Come in close contact with other people
Tinea corporis can spread easily. You can catch it if you come into
direct contact with an area of ringworm on someone's body. You can
also get it by touching items that have the fungi on them, such as:
 Clothing
 Combs
 Pool surfaces
 Shower floors and walls
Ringworm can also be spread by pets. (Cats are common carriers.)

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4. tinea pedis:
Athlete's foot (tinea pedis), also known as ringworm of the foot, is a
surface (superficial) fungal infection of the skin of the foot The most
common fungal disease in humans, athlete's foot, may be passed to
humans by direct contact with infected people, infected animals,
contaminated objects (such as towels or locker roo m floors), or the
soil
Who's At Risk?
Athlete's foot may occur in people of all ages, of all races, and of both
sexes. However, athlete's foot is more common in males than in
females. Children rarely develop athlete's foot.
Some conditions make athlete's foot more likely to occur:
 Living in warm, humid climates
 Using public or community pools or showers
 Wearing tight, non-ventilated footwear
 Sweating profusely
 Having diabetes or a weak immune system

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5. Tinea cruris
Tinea cruris: is a fungal skin infection of the groin. Some types of
fungal germs (fungi) are commonly found on human skin. They usually
do no harm. However, if conditions are right they can 'invade' the skin,
multiply and cause infection. The conditions fungi like best are warm,
moist and airless areas of skin, such as the groin


6. Tinea barbae:
Tinea barbae is a superficial dermatophyte infection that is limited to
the bearded areas of the face and neck and occurs almost exclusively
in older adolescent and adult males. The clinical presentation of tinea
barbae includes inflammatory, deep, and noninflammatory superficial
patches resembling tinea corporis or bacterial folliculitis
Tinea barbae is caused by the keratinophilic fungi (dermatophytes)
that are responsible for most superficial fungal skin infections. They

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infect the stratum corneum of the epidermis, hair, and nails. Several
enzymes, including keratinases, are released by dermatophytes, which
help them invade the epidermis. The mechanism that causes tinea
barbae is similar to that of tinea capitis. In both diseases, hair and hair
follicles are invaded by fungi, producing an inflammatory response.


7. Tinea Versicolor
Tinea versicolor is a fungal infection of the skin. It's also called
pityriasis versicolor and is caused by a type of yeast that naturally
lives on your skin. When the yeast grows out of control, the skin
disease, which appears as a rash, is the result.
The infection can happen for any of the following reasons:
 You have oily skin
 You live in a hot climate
 You sweat a lot
 You have a weak immune system

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Because the yeast grows naturally on your skin, tinea versicolor is not
contagious. The condition can affect people of any skin color. It's more
likely to affect teens and young adults.


Ecology
The dermatophytes causing human infections may have different
natural sources and modes of transmission:
Anthropophilic - These are usually associated with humans only;
transmission from man to man is by close contact or through
contaminated objects.
Zoophilic - These are usually associated with animals; transmission to
man is by close contact with animals (cats, dogs, cows) or with
contaminated products.

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Geophilic - These are usually found in the soil and are transmitted to
man by direct exposure.
Knowledge of the species of dermatophytes and source of infection are
important for proper treatment of the patient and control of the
source. Invasion by zoophilic or geophilic organisms may cause
inflammatory disease in man.
Geographic distribution: Dermatophytes occur worldwi de, but some
species have geographically limited distribution.
Morphology and culture:
The dermatophytes are filamentous fungi. They grow readily on fungal
nutrient mediums at 25–30 C. After 5–14 days, cultures with a woolly
appearance, in different colors, usually develop.
Pathogenesis and clinical pictures:
Dermatomycoses are infections that are transmitted directly by human
contact, animal-human contact or indirectly on inanimate objects
(clothes, moisture, and dust in showers, swimming pools, gyms). The
localization of the primary foci corresponds to the contact site. Thus
feet, uncovered skin (hair, head, facial skin) are affected most
frequently. Different species can cause the same clinical picture.

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Diagnosis:
Material suitable for diagnostic analysis includes skin and nails
scrapings and infected hair. The fungi ar e observed under the
microscope in a KOH preparation. Identification is based on the
morphology of the hyphae as well as on the macroconidia and
microconidia in the fungal cultures.

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Therapy:
Dermatomycoses can be treated with locally applied antimycotic
agents. In cases of massive infections of the hair, and above all of the
nails, the oral allylamine terbinafine or azoles can be used.
Griseofulvin is rarely used today.
Epidemiology and prevention:
Dermatophytes occur naturally all over the world. The geophilic
dermatophyte, M. gypseum, can cause infections in persons in
constant, intensive contact with the soil (e.g., gardeners). Prophylactic
measures for all dermatomycoses consist in a voiding direct contact
with the pathogen. Regular disinfection of showers can contribute to
prevention of athlete‟s foot, a very frequent infection.