1. Selected fungi of medical importance Please focus only on the information discussed!

2. 2 16.1 Characteristics of Fungi Fungi Share a Combination of Characteristics – Fungal life cycles involve a growth phase and reproductive phase – Molds grow as long, tangled filaments of cells in visible colonies – Yeasts are unicellular fungi Figure 16.2, page 478

3. Fungi and diseases caused Candida albicans- Candidiasis (vaginal yeast infection, thrush, diaper rash) Cryptococcus neoformans- Fungal meningitis. Lung infection in immunocompromised Dermatophytes (Tinea- Ringworm infection) – Trichophyton spp – Epidermophyton – Microsporum

4. 4 Candidiasis Often Is a Mild, Superficial Infection – Candida albicans can cause candidiasis when: the immune system is compromised or microbial populations in the body change – Vulvovaginitis, often called a “yeast infection,” involves: itching burning reddening swelling Discharge – Excessive antibiotic use may decrease protective bacteria in the vagina and intestine, allowing C. albicans to flourish Figure 16.19a, page 495

5. 5 – Oral candidiasis (thrush) involves white curd-like growth on the mucous membranes of the mouth – Onychia involves hardening, browning, and distortion of fingernails Figure 16.19b, page 495

6. Candida albicans

7. 7 16.4 Fungal Diseases of the Lower Respiratory Tract Cryptococcosis Usually Occurs in Immunocompromised Individuals – It is caused by Cryptococcus neoformans – C. neoformans is found in urban soil and pigeon droppings Figure 16.21a, page 497

8. Cryptococcus neoformans- India Ink

9. 9 – Inhaled cells penetrate to the air sacs of lungs – Cells can (rarely) pass into the bloodstream, infecting the brain and meninges Figure 16.21b, page 497

10. 10 Pneumocystis Pneumonia Can Cause a Lethal Pneumonia – It is caused by Pneumocystis jiroveci – It is a common infection in AIDS patients – P. jiroveci has a complex life cycle in the alveoli – It is usually transmitted through respiratory droplets

11. Fungi & Deep mycosis Histoplasma capsulatum Coccidioides immitis Blastomyces dermatitidis Pneumocystis carinii

12. Histoplasmosis Also called Spelunkers’ Disease Found in bat and bird droppings- Cave explorers (Spelunkers) Common in Mississippi, Ohio and St; Lawrence river valleys Caused by Histoplasma capsulatum Dimorphic fungus –Mold form in the environment and Oval intracellular yeasts in macrophages

13. 13 Histoplasmosis Can Produce a Systemic Disease – It is caused by Histoplasma capsulatum – It is found in dry, dusty soil, chicken coops, and bat caves – Most people suffer only mild influenza-like symptoms Figure 16.22a, page 498

14. Histoplasma in biopsy – Methanamine Silver stain

15. Blastomycosis Blastomycosis is endemic in the Southeastern United States, Common in Mississippi and Ohio valleys - riverbank soil Caused by Blastomyces dermatitidis Dimorphic fungus- mold in the environment and thick walled yeasts with broad based budding in the tissues

16. 16 Blastomycosis Usually Is Acquired Via the Respiratory Route – It is caused by Blastomyces dermatitidis – It is associated with dusty soil and bird droppings – Inhalation causes: lung lesions persistent cough chest pains – It can cause chronic pneumonia and may disseminate to other organs in AIDS patients Figure 16.22b, page 498

17. Coccidioidomycosis primarily is a respiratory infection Coccidioides immitis

18. 18 – It is caused by Coccidioides immitis – Inhalation of spores causing: a dry, hacking cough chest pains high fever – Rarely, infection disseminates to tissues such as meninges of the spinal cord Figure 16.23, page 499 Coccidioidomycosis Can Become a Potentially Lethal Infection

19. Coccidiodomycosis Also called Valley fever Geographic distribution- Semiarid regions of southwestern US, Central and South America Caused by Coccidiodes immitis It is a dimorphic fungus – mold in the soil (arthrospores) and Spherules with endospores in the tissues

20. C. Immitis in lung biopsy- Spherule

21. Pneumocystis carinii Very rare infection in population Widely distributed in nature Recognized as an opportunistic infection in severely malnourished children, premature babies and nursing homes Nowadays most commonly associated with AIDS Tiny fungus belonging to phylum ascomycota

22. Pneumocystis carinii- Fluorescence

23. P. Carinii – Lung Biopsy

24. Dermatophytosis is an infection of the body surface Tinea infections Multiple causes among fungi Symptoms Diagnosis Treatment

25. 25 16.3 Fungal Diseases of the Skin Dermatophytosis Is an Infection of the Body Surface – Species called dermatophytes cause dermatophytosis (tinea infections/ringworm) on the: skin, hair, nails – They can be transmitted by contact with Domestic animals Fomites like: floors, mats, towels Figure 16.18a, page 494

26. 26 – Symptoms include blister-like lesions with a thin fluid discharge – Treatment often involves changing the skin environment (moisture, pH, etc.) Figure 16.18b, page 494

27. Tinea pedis- Athlete’s foot

28. Skin scrapings – KOH prep Fungal hyphae

29. Other Fungi Also Cause Mycoses – In aspergillosis, conidia enter the body and grow as a mycelium It is commonly caused by Aspergillus fumigatus Surgery may be necessary to remove an aspergilloma from the lungs Aspergillus can also cause otomycosis in the ear, which can affect the heart Aspergillus niger is used in Beano™ to reduce flatulence 29

30. 30 – Fungal toxins are called mycotoxins – A. flavus and A. parasiticus produce carcinogenic aflatoxins Aflatoxins contaminate many agricultural products

31. Ergotism is caused by Claviceps purpurea, which grows on grains Ergot deposited in the grain can cause: – numbness – hot and cold sensations – seizures – paralysis of nerve endings Lysergic acid diethylamide (LSD) is a derivative of an alkaloid in ergot 31