7.Human Microbial Interaction between.ppt

Microbiology

1. Human and Microbial
Interaction
Rasheed Ahmed Khan
Instructor Nursing

2. Objective
At the completion of this unit learner will be able to
•Define normal flora
•Differentiate between resident and transient normal flora
•List at least three beneficial role of normal flora
•Define nosocomial infections
•List at least three measures to control nosocomial
infections
•Describe some pathogenic microbes and diseases
Pertusis, mumps, measles, polio, influenza ascariasis,
teaniasis and dermatomycosis.

3. What is Normal Flora ?
•Normal flora is the mixtureof microorganisms (bacteria
and fungi) that are regularly found at any anatomical site
of human body like, Skin, Eyes, Nose, Mouth, Ears,
Urogenetal tract, Elementry tract
•Vast majority of normal flora are bacteria
•The majority of these commensal bacteria are
anaerobes, meaning they survive in an environment with
no oxygen (GIT).
•Bacteria of the normal flora can act as opportunistic
pathogens at times of lowered immunity
•Composition of normal flora depends upon many various
factors: genetics, age, sex, stress, nutrition, and diet

4. Normal Flora of the Skin
•The most important sites are: Axilla, Groin, and Areas
between the toes
•The majority of skin microorganisms are found in the
most superficial layers of the epidermis and the upper
parts of the hair follicles
•Important bacteria:
Staphylococcus epidermidis
Micrococcus sp.
Corynebacteria sp.
Mycobacterium smegmatis

5. Normal flora of conjunctiva
•A variety of bacteria may be cultivated from the normal
conjunctiva but the number of organisms is usually small
(S.epidermidis, nonpathogenic corynebacteria,
Propionibacterium acnes) are dominant.
•S.aureus, streptococcus spp, Haemophilus spp, Neisseria
spp. are occasionally found.
•Pathogens usually are: Chlamydia trachomatis, S.aureus,
Neisseria gonnorhoae, streptococci, enterococci.

6. Normal flora of the Human Oral Cavity
•At birth the oral cavity is sterile but rapidly becomes
colonized from the environment, particularly from the
mother in the first feeding and then in other contact with
mother.
•Streptococcus salivarius is dominant –98% of the total
oral flora until appearance of the teeth.
•The mouth presents of different ecological situations with
age, and this corresponds with changes in the
composition of the normal flora.
•Streptococci, lactobacolli, staphylococci and
corynebacteria and anaerobes are common in oral cavity.

7. Normal Flora of the Gastrointestinal
Tract (GIT)
•In humans, the GIT flora are influenced by: Age, Diet,
Cultural conditions and The use of antibiotics.
•At birth the entire intestinal tract is sterile, but bacteria
enter with the first feed. The initial colonizing bacteria vary
with the food source of the infant.
•In breast-fed Bifidobacteria account for more than 90% of
the total intestinal bacteria.
•Switch to cow’s milk enterococci, lactobacilli and clostridia.
•E. coli, Klebsiella spp, Proteus spp, Enterococcus,
streptococci, Clostridia, Bacillus spp., Bacteroides and
many nonpathogenic protozoa are common.

8. Normal Flora of the Respiratory Tract
•The nostrils are always heavily colonized with
Staphylococcus epidermidis and corynebacteria with
Staphylococcus aureus.
•The upper respiratory tract (nasopharynx) predominantly
have non-hemolytic and alpha hemolytic streptococci and
Neisseria species
•Lower respiratory tract (trachea, bronchi, pulmonary
tissues) are uppon the normal conditions free of
microorganisms mainly because of the efficient cleansing
action of the ciliated epithelium which covers respiratory
tract
•Any bacteria reaching the lower respiratory tract are
removed by the action of this epithelia and also by
coughing, sneezing, swallowing, etc

9. Normal flora of the Urogenital Tract
•Upper urinary tract (kidneys, ureters, bladder) usually
sterile
•Lower parts of urethra may be colonized with a small
density of nonpathogenic S.epidermidis, streptococcus
spp, alfa hemolytic, enterococci, corynebacteria
•Vagina normally colonized with corynebacteria,
nonpathogenic streptococci, nonpathogenic staphylococci
small number of yeasts (Candida albicans) and
Lactobacillus lower pH protect against pathogenic flora
and also Trichomonas vaginalis
•About 80-90% infections of the urinary tract in woman
because of short distance from anus source of bacteria

10. Resident and Transient flora
Resident flora
•Consists of relatively fixed types of microorganisms
regularly found in a given area at a given age
•If disturbed, it promptly reestablishes itself
Transient flora
•Consists of nonpathogenic or potentially pathogenic
microorganisms that inhabit the skin or mucous
membranes for hours, or days
•It is derived from the environment, does not produce
disease, and does not establish itself permanently on the
surface
•Members of the transient flora are generally of little
significance so long as the normal resident flora remains
intact

11. Resident and Transient flora
•If the resident flora is disturbed, transient microbes may
colonize, proliferate, and produce disease

12. Benefits of the normal human flora
•Synthesis and excretions of vitamins (B group), vitamin
K (E.coli)
•prevent colonization of pathogens by competing for
attachment sites or for essential nutrients
•the normal flora also produces substances which inhibit
or kill nonindigenous species (pathogens)
•The normal flora in general stimulates the development
of certain lymphatic tissues (parts of immunity system in
GIT)
•The normal flora in general stimulate the production of
cross-reactive antibodies. It is known that the normal
flora induce immunological responses

13. Nosocomial infections
•Patient may get infected inside the hospital
It includes infections
Not present nor incubating at admission,
infections that appear more than 48 hours after
admission,
those acquired in the hospital but appear after
discharge

14. Methods to Prevent Nosocomial
Infections
•Hand Hygiene
•PPE based upon anticipated exposure
•Environmental measures
•Respiratory Hygiene/Cough Etiquette
•Safe Injection Practices
•Infection Control Practices for Special Procedures
•Proper waste disposal
•Measures to prevent sharps injuries
•Transmission based precaution

15. Tetanus
•Tetanus is an illness characterized by an acute onset of
hypertonia, painful muscular contractions (usually of the
muscles of the jaw and neck), and generalized muscle
spasms without other apparent medical causes.
•Caused by Clostridium Tetani
•Gram positive
•Spore-forming
•Anaerobic rod
•Spores of C. tetani are found in soils throughout the world

16. Tetanus
•Spores are very resistant to harsh conditions
Heat
Radiation
Chemicals
Drying
•Spores can survive for a long time in environment (100yrs
possibly)
•After gaining entry, C. tetani spores can persist in the body
for months, waiting for the proper low oxygen growth
conditions to develop
•When the oxygen levels of the surrounding tissue is
sufficiently low, the implanted C. tetani spore then
germinates into a new, active vegetative cell that grows
and multiplies and most importantly produces tetanus toxin

17. How it Develops?
•Spores that gain entry can survive for months to years.
Under anaerobic conditions, these spores geminate and
produce tetanospasmin. Tetanospasmin that is released
by the maturing bacilli is distributed via the lymphatic
and vascular circulations to the end plates of all nerves.
Tetanospasmin then enters the nervous system
peripherally at the myoneural junction and is transported
into neurons of the central nervous system (CNS).

18. How it Develops ?
•These neurons become unable of neurotransmitter
release. The neurons, which release gamma-
aminobutyric acid (GABA) and glycine, the major
inhibitory neurotransmitters, are sensitive to
tetanospasmin, leading to failure of inhibition of motor
reflex responses to sensory stimulation. This results in
generalized contractions of the musculature,
characteristic of a tetanic spasm. The shortest
peripheral nerves are the first to deliver the toxin to the
CNS, which leads to the early symptoms of facial
distortion and back and neck stiffness.
•Positive Spatula Test is used for diagnosis.

19. Medications Used for Treatment
•Diazepam (Valium) Most commonly used drug for
treatment of tetanic spasms and tetanic seizures.
Depresses all levels of CNS.
•Tetanus immune globulins Used to induce active
immunity against tetanus in selected patients.
•Penicillin G Interferes with synthesis of cell wall during
active multiplication, resulting in bactericidal activity
against susceptible microorganisms.
•Supportive treatment
•Nursing care

20. Complications
•Long bone fractures
•Glenohumeral and temporomandibular joint dislocations
•Adverse effects of autonomic instability, such as cardiac
dysrhythmias and hypertension
•Malnutrition
•Coma, neuropathies, and psychological aftereffects

21. Prognosis
•Prognosis is dependent on incubation period, time from
spore inoculation to first symptom, and time from first
symptom to first tetanic spasm.
•In general, shorter intervals indicate more severe
tetanus and a poorer prognosis.
•Patients usually survive tetanus and return to their pre
disease state of health.
•Recovery is slow and usually occurs over 2-4 months.

22. Measles
Hard Measles (Rubeola)
•Upper respiratory tract
infection
•High fever and coughing
•Kopliks spots in mouth
•Red skin rashes
Complication
•Bronchitis
•Pneumonia
•Otitis media
•encephalitis
German Measles (Rubella)
•Pink flat rashes
•Rashes spreading from face
•Tender lymph nodes
•Low grade fever
•A milder disease than hard
measles
Complication
•Congenital rubella syndrome
•Encephalitis but rare

23. Measles
Pathogen
•Measles (Hard Measles) = Measles (Rubeola) virus a
Paramyxovirus
•German Measles = Rubella virus a Togavirus
Reservoir =Human
Transmission
•Inhalation of droplets during contact with infected person
Incubation Period
•Paramyxovirus
Usually 14 days until rash appears
Contagious until 4 days after appearance of rash
•Togavirus = 14-21 days

24. Measles
Hard Measles (Rubeola)
Control
•Immunization with MMR
Usual treatment
•Bed rest
•Fluids replacement
•Antiviral chemotherapy
•Antibiotics to prevent secondary
bacterial infections
German Measles (Rubella)
Control
•Immunization with MMR for
young women before
pregnancy
•Determine immunity
•Isolation for 7 days after rashes
Usual treatment
•No chemotherapy available

25. Mumps
•Viral infection of salivary gland
•Usually parotid gland (parotitis)
•High grade fever
Complications
•Deafness
•Meningoencephalitis
•Mastitis
•Nephritis
•Thyroiditis
•Pericarditis
•Orchitis in men
•Oophoritis in women

26. Mumps
Pathogen =Mumps virus, a Paramyxovirus
Resivoir = Human
Transmission
•Direct contact and fomites via respiratory secretion,
droplets, saliva
Incubation period= 2-3 weeks, usually 18 days
Control
•Immunization with MMR FOR children and non immune
adults
•Respiratory isolation for hospitalized patient
Treatment = no specific chemotherapy

27. Polio
•An acute viral infection of the medulla oblongata, spinal cord
and nerves characterized by
•Fever, headache, nausea, vomiting, sore throat
•Muscles pain and spasms
•Neck and back stiffness with or without paralysis
•Usually asymptomatic or mild similar to influenza
•Most often infect children
Pathogen= polio virus types 1,2 and 3 small RNA enterovirus
 Type 1 = wild type most often cause paralysis
 Type 2,3= frequently vaccine associated
•Reservoir = human gastrointestinal tract

28. Polio
Transmission
•by direct contact or fecal oral route
•Virus is inhaled or ingested
•Contact with pharyngeal secretion and infected fecal material
•After vaccination with attenuated live vaccine
Incubation period =3-35 days usually 7-14 days
Control
•immunize all children and infants with a series of salk
inactivated polio vaccine Or sabin oral attenuated poliovirus
vaccine
•Isolate with enteric precaution
•Adequate sewage and water treatment precaution
Usual treatment
no any specific therapy provide assistance for paralytic patient.

29. Influenza (Flu)
•A specific acute viral respiratory infection characterized by
•Fever, chills, headache, cough and nasal drainage.
•Sometimes causing bronchitis, pneumonia and death in
severe cases.
•Nausea, vomiting and diarrhea are rare.
Pathogen
•influenza virus type A,B and C
•Type A is usually associated with pandemic and epidemic
Reservoir= humans
Transmission=respiratory secretions, direct contact, fomites,
Incubation period= 24-72 hours

30. Typhoid Fever
A gastroenteritis characterized by
•Abdominal pain
•Headache
•Nausea and vomiting and diarrhea
•Bactremia
•Constipation
•Intestinal hemorrhage
•Enlarged spleen and lymph nodes
•Sustained fever
Pathogen= Salmonella typhi

31. Typhoid Fever
Reservoir
•Humans, animals, domestic cattle, poultry, fish and others
Transmission= fecal oral route
•Incubation period 1-3 weeks
Control
•Isolation of hospitalized patient with enteric precaution
•Proper water purification prevent infection
•Effective sewage disposal
•Pasteurization of milk
Usual treatment
•fluid and electrolytes replacement
•Amoxicillin with cotrimoxazole or chloramphenicol
•For resistant strains quinolones and cephalosporins

32. Diphtheria
•An acute contagious respiratory disease with fibrinous
pharyngeal pseudomembrane causing myocardial and
neural tissues damage
Pathogen
•Corynebacterium diphtheriae, pleomorphic, gram-positive
bacilli
Reservoir= Humans
Transmission
•Air born droplet,
•Direct contact,
•Contaminated fomites,
•Raw milk
Incubation period= 2-5 days

33. Diphtheria
Control
•Immunization with DPT and DT
•Patient isolation
•Quarantine
•Disinfection of all fomites
Usual treatment
•Administer antitoxin in known and strongly suspected cases
erythromycin or penicillin
•Treat carriers with erythromycin or penicillin

34. Cholera
•An acute enteric diarrheal disease with watery stool,
vomiting, rapid dehydration, loss of blood volume, shock,
death frequently results if untreated.
Pathogen
•Vibrio cholerae, gram negative bacillus
Reservoir
•Humans and environmental reservoirs
Transmission= Fecal oral route
Incubation period= 1-5 days

35. Cholera
Control
•Isolation of hospitalized patient
•Disinfection of feces, vomitus, hands, linen, and fomites
•Vaccination in some countries
•Prophylactic tetracycline for exposed families
Usual treatment
•Fluids and electrolytes replacement therapy
•Tetracycline, cotrimoxazole, furazolidone chemotherapy
to shorten duration of disease

36. Pertussis(Whooping Cough)
•An acute bacterial childhood (usually) infection.
•The initial catarrhal (inflammatory) stage produces mild
symptoms resembling the common cold
•The second paroxysmal (symptomatic) stage is marked by
uncontrollable coughing in an attempt to expel the thick
mucus in the trachea and bronchi
•Pneumonia may be complication
Pathogen = Bordetella pertussis
Reservoir = Human respiratory tract
Transmission= Air born via droplet through coughing
Incubation period= usually 7-10 days up to 21 days

37. Pertussis
Control
•Vaccination of all young children with DPT
Usual treatment
•Erythromycin, tetracycline, or chloramphenicol

38. Tuberculosis
•An acute or chronic mycobacterial infection of the pulmonary
tract
•Infected patient shows a positive hypersensitivity skin test
and pulmonary tubercles may be seen on chest x-rays.
Pathogen = Mycobacterium tuberculosis
Reservoir = Humans, cattle rarely
Transmission
•Air born, droplet,
•Direct contact,
•Milk and contact with infected cattle
Incubation period= 4-12 weeks

39. Tuberculosis
Control
•Vaccination with BCG
•Tuberculin test of human and cattle
•Chest x-rays and treatment of tuberculosis skin test positive
individuals
•Preventive treatment of close contacts of infected individuals
Usual treatment
•A combination of antimicrobial drugs such as
•Isoniazid (INH)
•Rifampacin
•Streptomycin
•Ethambutol
•Parazinamide

40. Dermatocycosis
•Fungal lesions on skin (tinea corporis) scalp (tinea capitis)
groin (tinea cruris) foot (tinea pedis) and nails (tinea
unguium)
Pathogen
•various species of microsporum, epidermoton, filamentous
fungi
Reservoir= Humans, animals, and soil
Transmission = Direct or indirect contact with fungal spores
Incubation period= 4-14 days
Control = keep susceptible areas clean and dry
Usual treatment
•topical application of miconazole, clotrimazole,
•Oral griseofulvin for scalp and nail infection