Microbiology A Systems Approach Test Bank

Correct Answer: A

Rationale: The correct answer is A: Malaria. Two weeks after hemotransfusion, the onset of fever indicates a possible bloodborne infection. Malaria is a protozoal disease transmitted through infected blood, causing symptoms like fever. Toxoplasmosis, Leishmaniasis, and Amebiasis are not typically associated with fever following hemotransfusion. Malaria fits the timeline and mode of transmission in this scenario.

Correct Answer: A

Rationale: The correct answer is A: Psittacosis. This disease is transmitted via aerosols containing dried bird droppings or respiratory secretions from infected birds. When these aerosols are inhaled, the bacteria causing psittacosis enter the respiratory system and infect the individual. - B: Shigellosis is transmitted through contaminated food or water, not via aerosols. - C: Leptospirosis is transmitted through contact with water, soil, or food contaminated with the urine of infected animals, not via aerosols. - D: Giardiasis is transmitted through ingesting contaminated food or water, not via aerosols. Therefore, Psittacosis is the only disease in the list that is transmitted via aerosols, making it the correct answer.

Correct Answer: B

Rationale: The correct answer is B: Gram's staining method. The rationale for this is as follows: Gentian violet and Lugol's solution are used as primary and mordant stains in the Gram's staining method. Spiritus 960 is used as a decolorizer, and water fuchsin is used as a counterstain. This staining method is commonly used in microbiology to differentiate bacteria into Gram-positive and Gram-negative based on their cell wall characteristics. A: Leffler's staining method is used for the identification of diphtheria bacilli. C: Ziehl-Neelsen's staining method is used for acid-fast bacteria like Mycobacterium tuberculosis. D: Neisser's staining method is used for the identification of Neisseria species. In summary, the use of specific reactives and stainers in the question indicates the application of the Gram's staining method for bacterial differentiation.

Correct Answer: C

Rationale: The correct answer is C: Beta lactamase. This enzyme is produced by bacteria to break down the beta-lactam ring structure of penicillins, rendering them ineffective. Beta lactam ring (A) is part of the penicillin molecule, not an enzyme. MRSA (B) stands for methicillin-resistant Staphylococcus aureus, a type of bacteria resistant to certain antibiotics, not an enzyme. Aminoglycoside ring (D) refers to a different class of antibiotics and is not related to penicillin resistance in bacteria.

Correct Answer: A

Rationale: The correct answer is A: Dysenteric amoeba. This is because dysenteric amoebas can cause asymptomatic parasitosis, where a healthy person carries cysts that can infect others. Dysenteric amoebas are known to infect the intestines and can be transmitted through contaminated food or water. Choice B, Malarial plasmodium, causes malaria transmitted through mosquitoes. Choice C, Enteral trichomonad, causes diarrhea and is transmitted through contaminated water. Choice D, Dermatotropic leishmania, causes skin lesions and is transmitted through sandfly bites. These choices do not fit the scenario of asymptomatic parasitosis in public catering establishments.