Department Of Medical Microbiology & Parasit OmpathStudy

M ount Kenya University UNIVERSITY EXAMINATION 2022/2023 MEDICAL SCHOOL DEPARTMENT OF MEDICAL MICROBIOLOGY BACHELOR OF MEDICINE AND BACHELOR OF SURGERY (MBChB) UNIT CODE : MBMM 2400 UNIT TITLE : Principles of Microbiology and Parasitology DATE : Tuesday, 11th July 2023 TIME : 8:00 AM – 10:00 AM DURATION : 2 Hours --- INSTRUCTIONS Answer all questions in Sections A and B. Answer any TWO (2) questions in Section C. --- SECTION A: MULTIPLE CHOICE QUESTIONS (35 MARKS) ## Principles of Microbiology and Parasitology & Medical Parasitology Complete MCQ Answer Key with Explanations --- SECTION A: PARASITOLOGY MCQs 1. Nitazoxanide is BEST for treatment of? Options: A. Amoebiasis B. Trichomoniasis C. Giardiasis D. Chagas disease E. Loasis Answer: C. Giardiasis Explanation: Nitazoxanide is a broad-spectrum antiparasitic drug that is particularly effective against Giardia lamblia. While it has some activity against other parasites, its primary indication and best efficacy is for giardiasis treatment. Why other options are incorrect: A. Amoebiasis: Metronidazole is the drug of choice B. Trichomoniasis: Metronidazole is the preferred treatment D. Chagas disease: Benznidazole or nifurtimox are used E. Loasis: Diethylcarbamazine (DEC) is the treatment of choice --- 2. Metronidazole parasite site of target is? Options: A. RNA B. DNA C. Ribosomes D. Cytoskeleton Answer: B. DNA Explanation: Metronidazole is activated by reduction in anaerobic organisms, forming reactive intermediates that damage DNA by causing strand breaks and preventing DNA replication. Why other options are incorrect: A. RNA: Not the primary target of metronidazole C. Ribosomes: Target of antibiotics like chloramphenicol, not metronidazole D. Cytoskeleton: Target of drugs like benzimidazoles, not metronidazole --- 3. Which parasite causes vitamin B12 deficiency? Options: A. Ancylostoma braziliense B. Toxocara canis C. Enterobium vermicularis D. Diphyllobothrium latum Answer: D. Diphyllobothrium latum Explanation: Diphyllobothrium latum (fish tapeworm) causes vitamin B12 deficiency by competing with the host for vitamin B12 absorption in the small intestine, potentially leading to megaloblastic anemia. Why other options are incorrect: A. Ancylostoma braziliense: Causes cutaneous larva migrans B. Toxocara canis: Causes visceral larva migrans C. Enterobium vermicularis: Causes pinworm infection with perianal itching --- 4. Which of the following parasites is associated with achlorhydria? Options: A. Dientamoeba fragilis B. Trichomonas vaginalis C. Giardia intestinalis D. Leishmania tropica E. Toxoplasma gondii Answer: C. Giardia intestinalis Explanation: Giardia intestinalis is associated with achlorhydria (absence of gastric acid) as the low acid environment facilitates Giardia survival and establishment in the small intestine. Why other options are incorrect: A. Dientamoeba fragilis: Causes colitis, not associated with achlorhydria B. Trichomonas vaginalis: Urogenital parasite, not related to gastric acid D. Leishmania tropica: Causes cutaneous leishmaniasis E. Toxoplasma gondii: Intracellular parasite, not gastric-related --- 5. Which of the following parasites is associated with pyosalpingitis? Options: A. Amoeba species B. Trichomonas species C. Giardia species D. Leishmania species E. Onchocerca volvulus Answer: B. Trichomonas species Explanation: Trichomonas vaginalis can cause ascending urogenital infections leading to pyosalpingitis (infection of the fallopian tubes) and pelvic inflammatory disease. Why other options are incorrect: A. Amoeba species: Primarily cause intestinal or hepatic infections C. Giardia species: Intestinal parasite, not urogenital D. Leishmania species: Cause cutaneous, mucocutaneous, or visceral leishmaniasis E. Onchocerca volvulus: Causes river blindness --- 6. Ground itch is produced by? Options: A. Necator americanus B. Ascaris lumbricoides C. Enterobium vermicularis D. Diphyllobothrium latum Answer: A. Necator americanus Explanation: Ground itch is caused by skin penetration of hookworm larvae, particularly Necator americanus and Ancylostoma duodenale, as they enter through bare feet in contact with contaminated soil. Why other options are incorrect: B. Ascaris lumbricoides: Transmitted through ingestion of eggs, not skin penetration C. Enterobium vermicularis: Transmitted through ingestion of eggs D. Diphyllobothrium latum: Transmitted through eating undercooked fish --- 7. Which one is associated with nocturnal pruritus ani? Options: A. Necator americanus B. Ascaris lumbricoides C. Enterobium vermicularis D. Diphyllobothrium latum Answer: C. Enterobium vermicularis Explanation: Enterobium vermicularis (pinworm) causes nocturnal pruritus ani because female worms migrate to the perianal area at night to lay eggs, causing intense itching. Why other options are incorrect: A. Necator americanus: Causes anemia and abdominal symptoms B. Ascaris lumbricoides: Causes intestinal obstruction and respiratory symptoms D. Diphylloboth