Opportunistic mycoses ASPERGILLOSiS .pptx

Opportunistic mycoses K R.pptx

1. OPPORTUNISTIC MYCOSES : ASPERGILLOSiS K R MICRO NOTES 1

2. Opportunistic MYCOSES Opportunistic mycoses are a type of systematic infections Caused by Normal flora that becomes opportunistic in a immunocompromised people such as AIDS patients, post covid 19 patients etc.. With opportunistic infections, the equation is tilted in favor of "disease" because resistance is lowered when the host is immunocompromised. The fungi most frequently isolated from immunocompromised patients are saprophytic (i.e. from the environment) or endogenous (a commensal).  The most common species are  Candida  species,  Aspergillus  species, and  Mucor  species. K R MICRO NOTES 2

3. ASPERGILLOSIS Aspergillosis is an infection caused by  Aspergillus , a common mold (a type of fungus) that lives indoors and outdoors. Most people breathe in  Aspergillus  spores every day without getting sick. However, people with weakened immune systems or lung diseases are at a higher risk of developing health problems due to  Aspergillus . In some people, the spores trigger an allergic reaction. Other people develop mild to serious lung infections. The most serious form of aspergillosis — invasive aspergillosis — occurs when the infection spreads to blood vessels and beyond.There are different types of aspergillosis. Some types are mild, but some of them are very serious. The types of health problems caused by  Aspergillus  include allergic reactions, lung infections, and infections in other organs. K R MICRO NOTES 3

4. Aspergillosis - Classification Kingdom : Mycota Division : Ascomycota Sub division : Eumycotina Class : Ascomycetes Order: Aspergillales Family : Aspergillaceae Genus : Aspergillus K R MICRO NOTES 4

5. Aspergillosis - Types Allergic bronchopulmonary aspergillosis (ABPA) : Occurs when  Aspergillus  causes inflammation in the lungs and allergy symptoms such as coughing and wheezing, but doesn’t cause an infection. Allergic  Aspergillus  sinusitis : Occurs when  Aspergillus  causes inflammation in the sinuses and symptoms of a sinus infection (drainage, stuffiness, headache) but doesn’t cause an infection. Azole-Resistant  Aspergillus fumigatus:  Occurs when one species of  Aspergillus, A. fumigatus,  becomes resistant to certain medicines used to treat it. Patients with resistant infections might not get better with treatment. Aspergilloma : Occurs when a ball of  Aspergillus  grows in the lungs or sinuses, but usually does not spread to other parts of the body. Aspergilloma is also called a “fungus ball.” Chronic pulmonary aspergillosis : Occurs when  Aspergillus  infection causes cavities in the lungs, and can be a long-term (3 months or more) condition. One or more fungal balls (aspergillomas) may also be present in the lungs. Invasive aspergillosis : Occurs when  Aspergillus  causes a serious infection, and usually affects people who have weakened immune systems, such as people who have had an organ transplant or a stem cell transplant. Invasive aspergillosis most commonly affects the lungs, but it can also spread to other parts of the body. Cutaneous (skin) aspergillosis : Occurs when  Aspergillus  enters the body through a break in the skin (for example, after surgery or a burn wound) and causes infection, usually in people who have weakened immune systems. Cutaneous aspergillosis can also occur if invasive aspergillosis spreads to the skin from somewhere else in the body, such as the lungs. K R MICRO NOTES 5

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7. General characteristics Of aspergillus spps. It is commonly found in soil, with a saprophytic mode of nutrition, obtaining its nutrients from dead and decaying matter. The saprophytic nature of  Aspergillus  spp means they fully depend on environmental materials, which allows them to produce enzymes such as amylase that breaks down compounds into simple products that can be absorbed by the vegetative hyphae. High production of the amylase enzymes enables the consistent decaying of all organic materials within their subsequent environment and availability of more food materials for utilization during reproduction and growth. It is a spore-forming mold fungus reproduces asexually by producing spores in the form of conidia ( conidium: singular). The conidia are densely found in the air. In the availability of moisture, warmth, and nutrients, the conidia can germinate forming hyphae that later develop the fungal mycelium. The hyphal filament allows the fungus to grown and reproduce. The conidial spores are densely produced into the air during sporulation and are consistently inhaled by humans and animals in hundreds per day. It can be pathogenic in humans causing severe allergic reactions and respiratory opportunistic fungal infection known as  Aspergillosis , especially in immune-compromised individuals. Some of the common  Aspergillus  spp include: Aspergillus fumigatus,Aspergillus niger, Aspergillus flavus, Aspergillus nidula, Aspergillus clavans K R MICRO NOTES 7

8. Habitat of  Aspergillus Aspergillus is a fungus belonging to the Aspergillus group of fungi, Their ecological niche is in soil, surviving and growing on organic debris. It is one of the most common ubiquitous airborne saprophytic fungi It is predominantly found in the air hence it is constantly inhaled in the form of conidia by humans and animals. K R MICRO NOTES 8

9. Aspergillus - morphology The morphology of  Aspergillus  is defined by the hyphal conidia and conidiophores. They have a green spiked conidia i.e the surface has small spikes covering its surface. The conidia are 2.5-3um in diameter. The conidia have a smooth surface or spiked (spinose). Conidia are produced in column chains that are basipetal (facing downwards) from green phialides of 6-8 by 2-3um in size. Some  A. fumigatus  strains produce white conidia because they lack pigment. Conidia chains are produced directly on broadly clavate vesicles (20-30um in diameter) in the absence of metulae (one of the outermost branches of a conidiophore from which flask-shaped phialides radiate). K R MICRO NOTES 9

10. Pathogenesis of Aspergillosis Aspergillus fumigatus  is a highly ubiquitous fungus, known to spread its spores in dense numbers that can be inhaled by both humans and animals in over 100spores in a day. 1. Transmission They are transmitted by the inhalation of fungal spores (conidia). They are found ubiquitously in the environment and they are continuously inhaled by humans. When inhaled by persons with a weakened immunity of the respiratory tract, they can cause opportunistic infections. K R MICRO NOTES 10

11. 2.HOST COLONIZATION After inhalation by immune defected individuals, the fungal spores attach to the epithelial cells that are damaged by immune therapies such as drugs such as corticosteroids, radiations, that allow the spores to colonize the damaged surface. A unique characteristic of the  Aspergillus fumigatus  conidia is there ability to evade the innate immune defenses by cilia and the mucosal lining of the respiratory tract. Conidia spores have gliotoxin, helvolic acid, and fumagillin which assist in evading the mucociliary layer of the respiratory tract. The conidia then bind to the defected epithelial cells of the respiratory tract and membranes within the tract by the help of sialic acid. Sialic acid helps in the asexual reproduction in pathogenic Aspergilli. The conidia are then engulfed by macrophages forming a phagosome where they germinate preventing apoptotic cell death of epithelial cells. The fungi also produce protease enzymes that assist in the colonization of lung tissues, elastase enzyme which degrades the host tissues in the lungs. 3.EVADING OF MACROPHAGE MECHANISM Acute inflammation causes a reduction in the effector mechanism of alveolar macrophages. This causes the  Aspergillus fumigatus  to invade and kill the macrophages, leading to inflammations immediately the fungal conidia starts to germinate. Conidial spores are recognized by macrophages by a carbohydrate complex known as beta (1,3) glucal found of the surface of the spores. This complex binds to the dectin on the alveolar macrophages, activating macrophage phagocytosis and inflammation in the alveolar and the lung tissues. Additionally, conidia in the resting phase also have the ability to evade the macrophage mechanisms because of the presence of superoxide dismutases that acts as a reactive oxygen species (ROS) scavenger. K R MICRO NOTES 11

12. Dissemination During hyphal growth, the aerial hyphae start to invade the endothelial cells of the blood vessels in the lungs. They first start to invade the outer blood vessels, moving through the endothelial cells into the inner part of the blood vessels. When the hyphae reach the blood, they fragment and start to circulate in the bloodstream and attach to the luminal of the endothelial cells. They then grow into the abluminal parts and continues to spread within the bloodstream and the rest of the body. The body reacts by producing neutrophils that act by adhering and killing the hyphae but because of the defragmentation and spread, sometimes the number of neutrophils may be overwhelmed by the hyphal colonization. This may lead to an invasion of the pulmonary tissues and the vascular system causing thrombosis and tissue necrosis, This causes a hematogenous spread to other body organs and even to the brain and its tissues. K R MICRO NOTES 12

13. Signs and symptoms Different kinds of Aspergillosis Show different symptoms, but some common signs and symptoms May include: Pain in chest and bones Pneumonia Vision difficulties Blood in urine Less urine Headaches Chills Difficulty in breathing Cough and sputum production Blood in sputum Weight loss K R MICRO NOTES 13

14. Laboratory diagnosis of Aspergillosis Diagnosing an infection caused by Aspergillus fungus can be difficult and depends on the type of aspergillus infection. Here are some tests that the doctor would suggest for a patient: Imaging Test: A chest X-ray or computerized tomography (CT) scan - a type of X-ray that produces more detailed images - may reveal if there are any cavities or fungal balls in the lungs. K R MICRO NOTES 14

15. 2: Bronchoscopy and Biopsy: Bronchoscopy involves inserting a long, flexible tube with a camera at the end into the lung passages, via nose or mouth. During the procedure, a small piece of infected tissue (biopsy) may be removed to test for invasive aspergillosis. K R MICRO NOTES 15

16. 3: Skin Prick Test: If ABPA is suspected, skin prick test is usually done. The skin is pricked with a needle containing a small amount of aspergillus mold. If the person is allergic, the area of skin will develop a hard red bump. K R MICRO NOTES 16

17. Respiratory secretion (sputum) test : The sputum of the patient is stained with a particular dye and examined for the presence of Aspergillus filaments under a microscope. The sputum is also placed in a suitable culture medium that promotes the growth of the fungus. K R MICRO NOTES 17

18. Treatment of Aspergillosis Invasive Aspergillosis is effectively treated with voriconazole. However, the species seems to have developed resistance to azoles and therefore a combination of voriconazole with Amphotericin-B or any antifungal drugs can be used. In rare cases, surgery is used to remove the infected tissue, although this is risky since patients with IA are already very ill. As a preventative measure, patients at high risk of developing IA can be given anti-fungal drugs like aerosolized liposomal amphotericin B. The key to the treatment of invasive aspergillosis (IA) is early detection. Treat allergic forms of aspergillosis with corticosteroids or disodium cromoglycate.m K R MICRO NOTES 18

19. Prevention and Control Persons at risk of allergic infection and invasive aspergillosis should avoid exposure to conidial spores od Aspergillus spp. Bone-marrow transplant units should have filtered air-conditioning systems, monitored airborne contamination of patients, reduced visits to patients and application of measures that isolate patients and minimize the risks of exposure to Aspergillus conidia and molds, Preventive measures like low dosage of amphotericin B or Itraconazole for persons at risk. K R MICRO NOTES 19

20. ReferenceS https://www.cdc.gov/fungal/diseases/aspergillosis/index.html#:~:text=Aspergillosis%20is%20an%20infection%20caused,every%20day%20without%20getting%20sick https://microbenotes.com/aspergillus-fumigatus/#pathogenesis-of-aspergillus-fumigatus https://www.medindia.net/patients/patientinfo/aspergillosis.htm K R MICRO NOTES 20

21. Thank you K R MICRO NOTES 21