Mycology and Parasitology Textbook - PDF

173 MYCOLOGY by Mary Lux and Michele Zitzmann* Characteristics of Fungi 1. Reproductio...

173 MYCOLOGY by Mary Lux and Michele Zitzmann* Characteristics of Fungi 1. Reproduction CLASSIFICATION a. Sexual - fusion of 2 haploid nuclei; l. Zygomycota - ribbon-like aseptate spores - te)eomorph hyphae; sexual and asexual b. Asexual - mitotic division of haploid nucleus and budding production of 2. Ascomycota - septate; sexual and conidia - anamorph asexual; produce asci 2. Growth and morphology 3. Basidiomycota - septate; sexual; a. Diverse; from bacteria-like yeast to mushrooms; club fungi mushrooms h. Hyphae Laboratory Methods ❖ Tube-like structures with thick parallel walls 1. 10% KOH wet prep a. Clears debris and breaks down Ir$' Septate - has cross walls keratin from nails and hair ~ Aseptate (coenocytic) - has rare cross walls b. Use with specimen ❖ Several types: racquet, favic 2. Lactophenol cotton blue chandeliers, pectinate, nodular, a. Stains and kills organism spiral h. Use with culture material ❖ Mycelium is a mat of byphae i& Vegetative growth into 3. India ink - capsule of Crypto-. u 0.5 JO 3. Troph ,.m a. 1 nucleus b. Spiral groove - which gives it a " cork screw-type" motility Brool 6g/day Dipyli,li11111 eanfaw11 h. Stain with Sudan III, Sudan IV, or FLEAS Dog flea Oil Red 0 Rat flea Hymenolepis ,liminuta c. Characteristic orange-red staining Copepo.-1 (water ilea) JJ. fotum TICKS Bab~si,, o.,.,,. tick BUGS "f. (Tll2i Reduvid bug PARASITOLOGY SAMPLE QUESTIONS 205 1. Which of the following organisms causes 9. Which of the following can cause a fatal Visceral Larval Migrans? meningoencephalitis? A. Ancyclostoma brazilensis A. Balantidium coli B. Ascaris lumhricoides B. Entamoeba bistolytica C. Strongyloides stercoralis C. Naegleria fowleci D. Toxocara canis D. Toxoplasmosis gondii 2. Enterobius vermicularis infection is usually 10. The trophozoite of which organism is diagnosed by finding eggs from characterized by "falling leaf motility", two A. Cellulose tape preps. nuclei, an axostyle, 4 pair of flagella and a B. Concentrated stool samples. sucker on the underside of the organism? C. Iodine wet mounts from fresh stool. A. Clillomastix mesinili D. Sedimented stool samples. B. Giardia lamhlia C. Trichomonas hominis 3. The infective stage for Strongyloides D. Trichomonas vaginalis stercoralis is the A. Ova. 11. Which of the following eggs may not be B. Filariform larvae. detected in zinc flotation procedures? C. Rhabditiform larvae. A. Ascaris lumbricoides (fertile) D. Free living adult. B. Tricbiura trichuris C. Schistosoma mansoni 4. If humans ingest the egg of Taenia solium, they D. Taenia solium may develop A. Hydatid Disease. 12. Which trophozoite is suspected if ingested red B. Sparganosis. cells are seen on a saline wet prep? C. Trichinosis. A. Entamoeba coli D. Cystercercosis. B. Entamoeha histolytica C. E11dulir111:ix. 111:uw. 5. A silver methenamine stained slide of a D. lodamoeha butschlii bronchial washing from an AIDS patient is examined. Which of the following organisms is 13. Pregnant women are to avoid cleaning litter most likely to be identified? boxes of their house cats until after delivery to A. Cryptosporidium parvum prevent congenital infection of B. Toxoplasma gondii A. Ancylostoma caninum c.Strongyloides ster coralis B. Dipylidium caninum D. Pneumocystis jiroveci c. Toxocara cati D. Toxoplasma gondii 6. A blood smear showed crescent shaped gametocytes in several red cells. What is the 14. A patient visiting from overseas is hospitalized most probable identity of the organisms? due to suspected tuberculosis. The sputum A. Bahesia microti sample submitted to the laboratory is bloody B. Plasmodium falciparum with orange-brown flecks. Preliminary TB tests C. Plasmodium malariae are negative. Which of the following parasites D. Leishmania donovani may be suspected? A. Ascaris lumhricoides 7. Which organism is transmitted to humans by B. Fasciolopsis buski ticks and blood transfusions? C. Schistosoma japonicum A. Babesia D. Paragoni.mus westermani B. Wuchereria bancrofti C. Leishmania donovani 15. Which of the following cysts has a nucleus D. Trypanosoma cruzi with a prominent karyosome, a clear halo, no achromatic granules, no peripheral chromatin? 8. The ameba which can cause liver or lung A. Entamoeba bistolytica abscesses is B. Entamoeba hartmanni A. Balantidium coli C. Endolimax nana B. Dientamoeba fragilis D. Iodamoeba biitschlii C. Endolimax nana D. Entamoeba histolytica 206 16. Differential diagnosis of Cryptosporidium parvum and Cyclospora cayetanensis is based on: A. Clinical symptoms B. Oocyst size - Cyclospora is larger C. Oocyst morphology D. Acid fast stained smears - Cyclospora is NOT acid fast ANSWERS AND RATIONALE 1. D 6. B Dog & Cat Ascarids (Toxocara canis and The crescent shaped gametocytes is cati) cause Visceral Larval Migrans. Option A characteristic of P. falciparum. (Dog and Cat Hookworms) causes Cut aneous Larval Migrans. Option B may cause pneumonia 7. A from migration through liver and lungs or bowel obstruction. Option C may cause abdominal There is documentation of Babesia pain, vomiting and diarrhea. transmission via blood transfusion as wel] as deer ticks. The other three options are not 2. A transmitted by a tick bite (Wucheria - mosquito, Leishmania - sandfly, T. cruzi - reduvid bug). The female migrates to the anal opening (usually at night) and lays eggs in the perianal 8. D opening. The cellulose tape (scotch tape) prep will pick up the eggs and when stuck to a slide A hallmark of E. histolytica is its ability to will allow microscopic viewing. form extrain.testinal abscesses. Options A a.nd B are not amebas and do not cause extraintestinal 3. B abcesses. Option C is an ameba but is non pathogenic. The filariform larvae produces a proteolytic enzyme which allows it to penetrate man's skin. 9. C 4. D N aegleria fowleri can cause primary amebic meningoencephalitis; infections may go Taenia solium causes cyster cercosis. Option undetected unless a direct wet prep of the CSF is A results from an infection with Echinococcus performed. granulosus. Option B occurs when man is the intermediate host of Diphyllobothrium latum. 10. B Option C occurs when the larval forms of Trichinella spiralis encysts in the muscle. Other choices have one nuclei and no sucker. 11. C 5. D Pneumocystis jiroveci causes interstitial The eggs of S. mansoni are too large and plasma cell pneumonia and is life threatening to heavy to float. Other eggs which may not be immunocompromised patients. Option A can demonstrated in the zinc flotation procedure are cause profuse diarrhea in AIDS patients and is infertile Ascaris and those with operculi such as identified using an acid fast stain. Option B Diphyllobothrium latum leads to involve the CNS with various 12. B neurological symptoms and i s diagnosed using serologic techniques. Option C may cause death The diagnostic feature of E. histolytica is the and has a high r ate of autoinfection in finding of ingested r ed cells in trophs. Options immunocompromised hosts but is diagnosed by A, C and D may exhibit ingested bacteria. characteristic ova or larvae in stool samples.  207 13. D The definitive host of T. gondii is the cat. Immunocompromised patients as well as pregnant women are advised to avoid cleaning litter boxes to prevent exposure. Most people exhibit few or no symptoms due to infections, hut immunocompromised patients may experience cyst rupture leading to internal lesions while pregnant women may pass the infection transplacentally leading to congenital problems. 14. D P. westei-mani, a lung trematode found in the far East and Africa, encapsulates in the lungs. The brownish-yellow eggs may be found in sputum or fecal samples. Eggs of options A, B and C are found in the stool. 15. C Options A and B exhibit peripheral chromatin. Option D has achromatic granules. 16. B Cyclospora is about twice the size of Cryptosporidium. Both organisms are acid fast (Cyclospora is variable) and have similar morphology and clinical symptoms. ~ Be able to recognize the more common parasite eggs, cysts or trophozoites from graphic images.