Medical Microbiology Test Bank

Correct Answer: A

Rationale: The correct answer is A: Rifampicin. Rifampicin can cause red-orange discoloration of bodily fluids like urine due to its metabolism. This phenomenon is harmless but alarming to patients. Isoniazid (B) can cause peripheral neuropathy, Pyrazinamide (C) can cause hyperuricemia, and Ethambutol (D) can cause optic neuropathy.

Correct Answer: D

Rationale: The correct answer is D: Gram-negative coccobacillus. Francisella tularensis is a Gram-negative coccobacillus because it has a unique shape that is between a coccus (spherical) and a bacillus (rod-shaped) and it stains pink/red in the Gram staining process. It is important to note that it is not a coccus (choice B) or a Gram-positive bacterium (choice A). Choice C is too general and does not specify the coccobacillus shape of F. tularensis. So, the correct answer is D due to its specific characteristics as a Gram-negative coccobacillus.

Correct Answer: A

Rationale: Rationale: 1. Dysenteric amoeba (Choice A) is the correct answer because it can exist asymptomatically in carriers and be transmitted through cysts. 2. Malarial plasmodium (Choice B) causes malaria, not carried asymptomatically in cysts. 3. Intestinal trichomonad (Choice C) causes trichomoniasis, not carried asymptomatically in cysts. 4. Dermatotropic leishmania (Choice D) causes skin lesions, not carried asymptomatically in cysts.

Correct Answer: B

Rationale: The correct answer is B: autoclaving. Autoclaving is a process that uses high pressure and steam to achieve temperatures above the boiling point of water, typically around 121-134�C. This high heat and pressure are effective in destroying spore forms of microorganisms, which are highly resistant structures that can withstand boiling temperatures. Autoclaving ensures the complete destruction of spores, making it an effective method for sterilization. Rationale: A: Pasteurization uses lower heat compared to autoclaving and is not sufficient to destroy spore forms. C: Freezing does not effectively destroy spore forms, as most microorganisms can survive freezing temperatures. D: Boiling, while effective for many microorganisms, may not be sufficient to destroy spore forms due to their high resistance, unlike autoclaving.

Correct Answer: C

Rationale: The correct answer is C: tapeworms. Taeniasis is specifically caused by tapeworms of the Taenia species, such as Taenia solium. These parasitic worms infect the intestines of humans through consumption of contaminated food or water. Ringworms (choice A), hookworms (choice B), and pinworms (choice D) are all different types of parasites that cause distinct infections in the body, not taeniasis. Tapeworms are the only organisms among the choices that are directly associated with taeniasis due to their unique life cycle and mode of infection.