OPPORTUNISTIC MYCOSES-MICROBIOLOGY {S1}

1. OPPORTUNISTIC MYCOSES-MICROBIOLOGY {S1} BY RANJEET RAMAN

2. Different opportunistic mycoses occur depending on the type of opportunity: Altered T-cell function (AIDS) à Mucocutaneous candida, Cryptococcosis, Pneumocystis, Histo Altered phagocytic function (neutropenia) à Candidiasis, Aspergillosis, Zygomycosis

3. Candida These yeasts are part of our normal flora. The most virulent and common species is ​Candida albicans. This is distinguished by the presence of germ tubes on the yeasts. ​Candida in general always has hyphae, pseudohyphae, and yeasts all at once.

4. Mucocutaneous candidiasis occurs in immunosuppressed patients, such as those with ​HIV, on steroids, or pregnant. Invasive candidiasis occurs in hospitalized patients, such as those with burns, trauma, ​catheters, or transplant patients.

5. This infection with disseminate in the blood and ​seed organs. Candida albicans has hydrolytic activity and host mimicry. Remember that it has reverse ​dimorphism, and converts between yeast and pseudohyphae with germ tubes.

6. Aspergilla All Aspergilla infections are opportunistic. Aspergilla have angular dichotomously ​branching septate hyphae. Invasive Aspergillosis occurs in severely immunosuppressed patients, such as those with ​neutropenia, bone marrow transplant recipients, on steroids, or in end stage AIDS.

7. The spores are inhaled, and invade lung parenchyma with their hyphae. They can ​colonize old TB cavities, creating a fungal ball.

8. Zygomycetes Zygomycetes such as Rhizopus have right angle branching non-septate hyphae. Invasive Zygomycosis most often seen in diabetics with acidosis!! Nasocerebral invasion ​that starts in sinuses and extends to the brain. it’s in diabetics

9. Cryptococcus Generally, these opportunistic infections are caused by Cryptococcus neoformans. Cryptococci are encapsulated!! The capsule inhibits phagocytosis. Cryptococcosis usually strikes T-cell compromised patients such as AIDS patients. ​It disseminates across the blood-brain barrier and causes meningoencephalitis.

10. Pneumocystis Generally, these opportunistic infections are caused by Pneumocystis carinii. It strikes patients with depleted cell mediated immunity, not neutropenic patients. Generally this means patients with HIV. Pneumocystosis is an alveolar-interstitial pneumonia.

11. Common Cutaneous and Mucosal Mycoses Superficial Mycoses Fungus is confined to the dead skin and doesn’t illicit inflammation. Cosmetic problem only. Tinea versicolor is a discoloration of the skin caused by the fungus Malassezia furfur. Under the ​microscope it appears as “spaghetti and meatballs” with clumps of yeasts and short hyphae.

12. Cutaneous Mycoses Fungus is confined to the mucosa, skin, hair, and nails, causing minor brisk inflammation. Mucosal/Cutaneous Candidiasis is most commonly caused by Candida albicans. This is an ​opportunistic infection with T-cell deficiency, such as with AIDS or heavy steroids. ​On mucosal surfaces it causes white plaques made up of both yeast and hyphae. ​On cutaneous surfaces it causes red, scalded lesions in intertriginous areas.

13. Dermatophytosis is classically called ringworm, and is the only fungi that is transmitted from ​person to person. The various manifestations are all caused by T. rubrum (“ringworm”). ​T. rubrum has long, branching, septae hyphae.

14. Tinea capitis is a ringworm of the scalp occuring only in children. Often from infected dogs. Tinea pedis is ringworm of the feet, also called “athlete’s foot.” Tinea unguium is a nail infection with extensive extra keratin production.