Eukaryotic Microbes

1. Eukaryotic Microbes MICROBIOLOGY LECTURES Sofronio Agustin Professor

2. Lesson Objectives: At the end of the lesson, the students should be able to: • Describe the biology of medically important eukaryotic microbes. • Describe the human diseases associated with these microbes including their diagnosis, treatment and prevention. • Describe the laboratory procedures used to recover, study and identify these microbes.

3. FUNGI • Mycology - study of the multicellular fungi and yeasts. • Fungi are aerobic to facultatively anaerobic organisms that grow best in sugar rich and acidic medium such as Sabouraud Dextrose Agar (SDA). • Many are saprophytic (live on decaying and dead tissues) and some are decomposers (food spoilage). • Out of 50,000 known species, only 100-150 are medically important.

4. Zygomycetes • Characterized by having aseptate hyphae, asexual sporangiospores contained in bag like sporangium andsexualzygospores. • Rhizopus nigricans a black mold growing on stale bread and cereal.

5. Ascomycetes • Characterized by having septate hyphae, asexual conidiospores borne on flasklike structures called phialides andsexualascospores contained in saclike ascus. • Aspergillus fumigatusa blue green mold ; frequent contaminant in the microbiology laboratory.

6. Basidiomycetes • Characterized by having septate hyphae, asexual conidiospores and sometimes assumes yeast formsandsexualbasidiospores borne on clublike basidium. • Cryptococcus neoformansa capsulated yeast causing fungal meningitis.

7. Deuteromycetes • Lack sexual stage but produce several forms of asexual spores. Also called “Fungi Imperfecti. • Most pathogenic fungi belong to this group.

8. Yeasts • Unicellular fungi • Reproduce by budding • Produces pasty or mealy bacterialike colonies on SDA. • Cell walls are rich in mannan and glucan.

9. Medically Important Yeasts Candida albicans Germ tube production in plasma is diagnostic Characteristically produces pseudohyphae and thick-walled chlamydospores.

10. Medically Important Yeasts Cryptococcus neoformans Encapsulated Yeast stained with India Ink Characteristically produces positive urease test.

11. Molds • The fungal thallus consists of hyphae. • A mass of hyphae is a mycelium.

12. Molds • Septate hyphae • Aspergillus sp. or Penicillium sp. • Aseptate or coenocytic hyphae • Rhizopus sp. or Mucor sp.

13. Mycoses • Superficial or cutaneous - affect skin, hair and nails • Subcutaneous – affect connective tissues below the dermis • Systemic – affect deep organs and blood • Opportunistic – part of normal microbiota affecting immunocompromised hosts

14. Superficial Mycoses Dermatomycoses • Commonly caused by dermatophytes, fungi belonging to the Genera: Trichophyton, Microsporum, and Epidermophyton • Also called “tinea” or “ringworm” infections Dermatophyte Macroconidia

15. Superficial Mycoses Tinea Capitis • Alopecia in affected areas • Endothrix invasion of hair shaft • Woods lamp for screening

16. Superficial Mycoses 1 2 3 1- Tinea corporis 2- Tinea pedis 3- Tinea cruris 4- Tinea unguium 5- Tinea barbae 5 4

17. Superficial Mycoses Tinea Versicolor • White irregular spots on dark skinned individuals • Reddish spots if fair skinned • Caused by Malazzesia furfur • “Spaghetti Meatballs” appearance in Lactophenol Cotton Blue stain

18. Superficial Mycoses Candidiasis • Caused by Candida albicans • Thrush and diaper rash in infants • Also Vulvovaginitis and penile infections

19. Subcutaneous Mycoses Sporotrichosis • Caused by Sporotrix schenckii • Fungi introduced via splinters and rose thorns • “Rosary bead” like nodules and lesions on extremities

20. Systemic Mycoses Histoplasmosis • Caused by Histoplasma capsulatum, a dimorphic fungus • Endemic in Ohio River Valley • Pulmonary lesions and calcifications common in Histoplasmosis

21. Systemic Mycoses Blastomycosis • Caused by Blastomyces dermatitidis, a dimorphic fungus • Endemic in the Southeastern U.S. • Pulmonary symptoms are common in Blastomycosis • Sometimes cause cutaneous infections

22. Systemic Mycoses Coccidiodomycosis • Caused by Coccidiodes immitis, an arthrospore producing fungus • Endemic in arid areas of Southwestern U.S. • Also called San Joaquin Valley Fever

23. Miscellaneous Mycoses • Fungemias – the presence of fungi and yeast in the blood may be caused by C. albicans, C. neoformans and other fungi. • Opportunistic mycoses – caused by Aspergillus, Mucor, Rhizopus and Candida species. • Both present problems in immunocompromised and oncologic patients.

24. Mycotoxicosis • Brought about by eating food contaminated with or exposure to fungal toxins • Aflatoxin produced by Aspergillus flavus is associated with liver diseases such as hepatoma

25. Mycetismus • Brought about by ingestion of hallucinogen producing and poisonous mushrooms • Muscarin a hallucinogen is produced by Amanita muscaria • Death cap is associated with a poisonous mushroom, Amanita phalloides

26. Fungal Allergens • “Sick Building Syndrome” is caused by a black mold growing on damp cellulose parts of buildings, Stachybotrys chartarum • Considered as an EID, it causes PulmonaryHemorrhagic Syndrome in infants.

27. Algae • Prototheca sp., a colorless algae is associated with Bursitis (inflammation of joints) • Dinoflagellates of Gymnodinium and Gonyaulax spp are associated with Paralytic Shellfish Poisoning. Their algal bloom is popularly referred to as Red Tide. Prototheca wickerhamii

28. PROTOZOA • Protozoology – the study of protozoa, unicellular eukaryotes that reproduce asexually by fission, budding, or schizogony or sexually by conjugation. • Protozoans are chemoheterotrophs that found in soil, water, and some reside in animal hosts. • Trophozoitestage - vegetative or feeding stage is frequently the cause of the pathology. • Cyst stage – non-feeding and resistant form that can withstand harsh environmental conditions. This is usually the infective stage.

29. Rhizopoda (The Amoebas) • Move by means of pseudopods • Entamoeba histolytica causes amoebic dysentery • Acanthamoeba castellanii causes eosinophilic meningitis

30. Archaezoa (The Flagellates) • No mitochondria; multiple flagella • Giardia lamblia causes intestinal giardiasis • Trichomonas vaginalis (no cyst stage) causes trichomoniasis

31. Euglenozoa • Flagellates with amoeboid forms • Naegleria fowleri causes Primary Amoebic Meningoencephalitis (PAM) • N. fowleri is a thermophile that survives as a flagellate in warm water at 45oC (113oF). It encysts during the winter months.

32. Blood Flagellates • Arthropod borne parasites with complex life cycles • Trypanosoma gambiense and T. rhodesiense causes African Sleeping Sickness; transmitted by Tse-tse flies. • Leishmania tropica causes Baghdad Boil or Aleppo Button; transmitted by Sandlies.

33. Ciliophora (The Ciliates) • Move by cilia • Complex cells • Balantidium coli is the only human parasite; pigs are the reservoir hosts.

34. Apicomplexa (Sporozoa) • Nonmotile organisms • Complex life cycles Genera: • Plasmodium • Babesia • Cryptosporidium • Cyclospora • Toxoplasma Babesia microti Cyclospora and Raspberries =>

35. Plasmodium (Malarial Parasite) • Transmitted by female Anopheles mosquito • Morphologic forms seen in erythrocytes are: ring forms, merozoites, and sporozoites Species: • Plasmodium vivax • P. ovale • P. malariae • P. falciparum

36. Plasmodial Life Cycle

37. Toxoplasma • Toxoplasmosis a disease of blood and lymphatics • Toxoplasma gondii a spore-forming protozoan • Cats are reservoirs • Pregnant women are at risk ; infants suffer from hydrocephaly

38. Cryptosporidia • Cryptosporidiasis is a zoonotic disease characterized by severe diarrhea with fluid and weight loss • Indicator disease for clinical stage of AIDS. • Natural waterways in U.S. are contaminated byCryptosporidium parvum oocysts due to livestock wastes Cryptosporidium Oocysts Acid Fast Stain Oocysts invading intestinal mucosa

39. HELMINTHS • Helminths are the parasitic worms studied in Parasitology • Eukaryotic, chemoheterotrophic, multicellular animals Phylum: Platyhelminthes (flatworms) • Class: Trematoda (flukes) • Class: Cestoda (tapeworms) Phylum: Nematoda (roundworms)

40. Trematoda • Trematodes are the blood flukes that use humans as the definitive host • Schistosomiasis is caused by: Schistosoma mansoni S. haematobium S. japonicum • Use snail intermediate hosts where asexual reproduction occurs. Cryptosporidium Oocysts Acid Fast Stain

41. Cestoda • Bodies of Cestodes or tapewormsconsist of scolex (head) for attachment and proglottids (flat body segments) • Taenia solium – pork tapeworm • Taenia saginata –beef tapeworm • Tapeworms acquire nutrition by absorption through their cuticle.

42. Nematodes : Eggs Infective for Humans Enterobius vermicularis

43. Nematodes : Larvae Infective for Humans Trichinosis

44. Nematodes : The Hookworms • Hookworms are the second most common nematode infecting humans (800 million worldwide) Two species: • Ancylostoma duodenale • Necator americanus • Infection is acquired by larval penetration of the host • Adult worms attach to intestinal mucosa and feed on blood of host causing anemia

45. Arthropods as Vectors • Phylum: Arthropoda (exoskeleton, jointed legs) • Class: Insecta (6 legs) • Lice, fleas, mosquitoes • Class: Arachnida (8 legs) • Mites and ticks • May transmit diseases (as vectors) • Biological vectors • Mechanical vectors

46. Arthropod Vectors