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Fungi and Protozoa Nestor T. Hilvano, M.D., M.P.H. Images Copyright by Bauman, Robert. 2009. Microbiology, With Diseases by Taxonomy, 3rd edition, Pearson.

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Presentation on theme: "Fungi and Protozoa Nestor T. Hilvano, M.D., M.P.H. Images Copyright by Bauman, Robert. 2009. Microbiology, With Diseases by Taxonomy, 3rd edition, Pearson."— Presentation transcript:

1 Fungi and Protozoa Nestor T. Hilvano, M.D., M.P.H. Images Copyright by Bauman, Robert Microbiology, With Diseases by Taxonomy, 3rd edition, Pearson Benjamin Cummings

2 Learning Objectives You should be able to: 1.State the mode of transmission for mycoses. 2.Identify the laboratory techniques used to distinguish pathogenic fungi. 3.Discuss briefly the clinical manifestations of common systemic fungal infections and its causative agents. 4.Describe pityriasis caused by Malassezia furfur. 5.Identify several emerging fungal pathogens seen among AIDS patients. 6.Compare and contrast protozoan infections caused by Giardia, Amoeba, Trypanosoma, Trichomonas, Plasmodium, and Toxoplasma. 7.Compare and contrast the three most common roundworm infections of humans.

3 Mycoses Mycology – study of fungi Mycoses – fungal infection classified as superficial, cutaneous, subcutaneous, or systemic infections Generally spread via inhalation, trauma, or ingestion; also by contact (candida & pneumocystis) Most are dimorphic - below 30˚C (mycelia composed of hyphae); at 37˚C (as yeast) Diagnosis – sabouraud dextrose agar culture; KOH preparation; GMS (Gomori methenamine silver) stain; direct immunofluorescent probes Rx – antifungal agents (amphotericin B; toxic); alternative drugs (ketoconazole, itraconazole, fluconazole)

4 Common Fungal Diseases A. Pathogenic systemic fungi Blastomycosis – Blastomyces dermatitidis Coccidiomycosis – Coccidioides immitis Histoplasmosis – Histoplasma capsulatum B. Opportunistic systemic fungi Aspergillosis – Aspergillus fumigatus, Aspergullus flavus Candidiasis – Candida albicans Cryptococcosis – Cryptococcus neoformans Pneumocystosis – Pneumocystis carinii C. Superficial, Cutaneous, and Subcutaneous fungi – by contact or environmental exposure

5 Blastomycosis Blastomycosis dermatitidis Prevalent in Mississippi – Ohio river basin 9X more common in male Inhaled dust →lung →blood →skin and bones Pulmonary blastomycosis – most common Granuloma (cutaneous blastomycosis 60-70%) Osteoarticular blastomycosis (30%) Spores convert to yeast forms

6 Coccidioidomycosis Valley fever (San Joaquin Valley Fever) Coccidioides immitis Prevalent in Southwestern US Inhaled in lungs→ spores germinate into spherule (parasitic form) →enlarges and generate more spores 60% - no or mild symptoms Fever, chest pain, rash, and pneumonia Subcutaneous lesion (granular material) Dx – identification of spherules in KOH; culture

7 Histoplasmosis Most common fungal pathogen in humans Histoplasma capsulatum Prevalent in Ohio- Mississippi valley Inhaled from bird droppings usually asymptomatic and resolve (95%) Chronic pulmonary histoplasmosis, chronic cutaneous histoplasmosis, systemic or ocular histoplasmosis (5%) - Granuloma in lung (resembles TB) * Spiny spores of H. capsulatum

8 Aspergillosis Aspergillus flavus Inhalation of spores aflatoxin→ liver CA Cause pulmonary diseases (noninvasive; manifest as allergy or asthma) In immunocompromised (IV drugs users, AIDS) - non-pulmonary (cutaneous) - systemic (often fatal) Raised red papules and necrotic

9 Candidiasis Candida albicans Infection from superficial to systemic - superficial→ deep invasion (low immunity)→ blood stream (catheter, surgery, etc.) - oral thrush - perianal in infants Dx - clusters of yeast and pseudohyphae Rx – antifungal drugs; reestablish normal flora

10 Cryptococosis Crptococcus neoformans Worldwide Affects immunocompromised Capsule; india ink as negative stain From inhaled spores or birds droppings Lung infection (self-limiting to chronic pneumonia) Meningitis (most common clinical form) Rx – amphotericin B

11 Pneumocystosis Pneumocystis jiroveci (P. carinii) Common opportunistic in AIDS Inhalation of droplets Form cysts in lungs (pneumonia) Fever, dyspnea, hypoxia, sometimes cough Dx - shadow on Chest X - ray Rx – trimethoprim and Sulfanilamide

12 Malassezia Infections Malassezia furfur – normal inhabitant of skin; various superficial infections Pityriasis (tinea versicolor) – depigmentation or hyperpigmentation Folliculitis, seborrheic dermatitis, and dandruffs Dx – UV illumination (pale green); KOH (budding yeast and hyphae) Rx – ketoconazole shampoos or topical zinc pyrithione, selenium sulfide, or propylene glycol

13 Protozoa Amoebiasis – Entamoeba histolytica Trypanosomiasis – African sleeping sickness (T. gambiense, T. brucei); Chaga ‘s disease (T. cruzi) Giardiasis – Giardia lamblia Trichomoniasis – Trichomonas vaginalis Malaria – Plasmodium vivax, P. falciparum, P. malariae Toxoplasmosis – Toxoplasma gondii

14 Amoebiasis Entamoeba histolytica – phagocytic; cysts with 4 nuclei; trophozoites with pseudopodia MOT - Fecal contamination containing cysts; travellers, refugees, immigrants Mild to severe diarrhea; amebic dysentery (bloody diarrhea) Form abscess in liver, spleen, lung, kidney, meninges, or brain. Dx – identification of cyst or trophozoites in stool or intestinal biopsy Rx – antiamoebic drugs (metronidazole) Prev – discontinue use of human waste as fertilizer; effective water Rx; good personal hygiene

15 Trypanosomiasis Flagellates African sleeping sickness – T. gambiense, T. rhodesiense, T. brucei MOT – bite from tsetse fly (trypanosoma reproduce in gut and migrate to salivary gland) → to lymph and blood (parasitemia) Acute febrile attack Episodic fever with lymphadenitis DIC Progressive brain dysfunction; fatal Rx – early Rx is effective * Glossina

16 Chaga’s Disease Trypanosoma cruzi MOT – bite from blood sucking kissing bug (kiss people on lips while asleep) → lymph and blood → multiplies in tissues (pseudocysts) Fever, lymphadenitis Acute form – unnoticed Chronic form – up to 20 yrs. Later; myocarditis, meningitis, chronic heart disease (5% mortality)

17 Giardiasis Giardia intestinalis (G. lamblia) – with many flagella; looks like a “head with face” One of most common water- borne gastroenteritis in US Cysts form in duodenum, shed in feces→ mild indigestion for days/weeks → diarrhea → chronic giardiasis (bloating, nausea, vomiting, malabsorption, weight loss) Rx – metronidazole

18 Trichomoniasis Trichomonas vaginalis – 3-4 flagella; trophozoites, no cyst form Common sexually transmitted parasitic infection Both sexes – burning, itching sensation of genitalia, some discharge Vaginitis in women Urethritis or cystitis in men, but often asymptomatic (ping-pong disease) Dx – identify trophozoites in vaginal and urethral secretions Rx – metronidazole Prev – abstinence, monogamy, condoms

19 Toxoplasmosis Toxplasma gondii Wild/ domestic mammals and birds – major reservoirs Cat – definitive hosts (protozoan reproduce sexually) Human infected by ingesting undercooked meat with parasites; ingestion or inhalation with contaminated soil; can cross placental to fetus Fever to pneumonia, CNS damage, blindness Pregnant women – stillbirth, jaundice, pneumonia, myocarditis, encephalitis; death Lymphadenitis in healthy person Prev – thoroughly cooking meat; avoid contact with contaminated soil

20 Malaria Plasmodium vivax (clinical relapse), P. falciparum (most deadly), P. malariae Vector – Anopheles mosquitoes Life cycle has 3 stages 1. exoerythrocytic – sporozoites (infective stage to human) travel to liver, then rupture to release merozoites (pathogenic to human) 2. erythrocytic – merozoites infect RBC; become trophozoites and undergo schizogony to produce merozoites, some develop to gametocytes 3. sporogonic – mosquitoe ingest gametocytes (infective stage to mosquito), develop into gametes, become oocyst, divides into sporozoites, completing the cycle. RBC lyse to release merozoites and waste → shaking chills, high fever (104˚F), sweating Rx – chloroquine, pyrimethamine with sulfadoxine Prev – prophylactic quinine for travel to endemic places; vector control; personal protection

21 Helminthic parasites (Worms) 1. Cestodes (tapeworms) a) Taenia saginata (beef tapeworm) b) Taenia solium (pork tapeworm) 2. Trematodes (flukes) a) blood flukes – Schistosoma (schistosomiasis) b) liver flukes – Fasciola (liver atrophy and cirrhosis) 3. Nematodes (round worms) a) Ascaris lumbricoides – ascariasis (worldwide; longest/largest) b) Enterobius vermicularis - pinworm (most common in US) c) Wuchereria bancrofti - filaria (South America, Caribbean, Trophics)

22 Filariasis Wuchereria bancrofti – threadlike (filarial) nematode Infect the lymphatic system and subcutaneous tissues Transmitted by mosquitoes (culex, aedes, and anopheles)- ingest microfilariae from infected host, then develop into larvae in gut and migrate to salivary glands, passed to human and develops into adults Asymptomatics for yrs. Elephantiasis (tissue enlarge and harden) Dx – identify microfilariae or immunoassays Rx – diethylcarbamazine citrate Prev – avoidance of mosquitoes

23 Homework 1. Identify the fungal agent and most common clinical manifestation/s (lesion/s) of the following: candidiasis, aspergillosis, cryptococcosis, blastomycosis, coccidiodomycosis, tinea versicolor; and histoplasmosis. 2. What fungal infection is commonly associated with AIDS (HIV)? 3. Compare and contrast amoebiasis and giardiasis. 4. Identify the risk factors and preventative measures for Trichomonas vaginalis infection. 5. Describes the types of helminthic worms. 6. Discuss African sleeping sickness and Chaga’s disease. 7. Discuss malarial infection as to manner of transmission, clinical manifestations, and preventions.


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