microbiology chapter 1 test bank

Correct Answer: A

Rationale: The correct answer is A: aspergillosis and candidiasis. Detection of galactomannan and free mannan is commonly used in diagnosing these fungal infections. Galactomannan is a component of the cell wall of Aspergillus species, while free mannan is associated with Candida species. This detection method helps in identifying these specific fungal infections accurately. B: Syphilis is caused by a bacterium, Treponema pallidum, and is not diagnosed using galactomannan or free mannan detection. C: Leptospirosis is a bacterial infection caused by the Leptospira species and is not diagnosed using galactomannan or free mannan detection. D: HIV infection is a viral infection caused by the human immunodeficiency virus and is not diagnosed using galactomannan or free mannan detection.

Correct Answer: B

Rationale: The correct answer is B: Typhoid fever, Brucellosis. Both Typhoid fever and Brucellosis are bacterial infections that can lead to bacteremia, the presence of bacteria in the bloodstream. In Typhoid fever, the causative agent Salmonella typhi can enter the bloodstream, causing bacteremia. Similarly, Brucellosis, caused by Brucella species, can also result in bacteremia. Choice A is incorrect because bacteremia is not typically observed in Diphtheria. Choice C, Cholera, is caused by a toxin-producing bacterium and does not usually lead to bacteremia. Choice D, Dysentery, is a condition characterized by bloody diarrhea and is primarily caused by parasites or bacteria that typically do not lead to bacteremia.

Correct Answer: A

Rationale: The correct answer is A: Balantidium coli. Balantidium coli is a large ciliated protozoa with a kidney-shaped macronucleus, commonly found in the feces of individuals with dysentery symptoms. Its morphology matches the description given in the question, making it the most likely causative agent. Summary of other choices: B: Entamoeba histolytica - This is not the correct answer because Entamoeba histolytica is a small amoeba with no cilia and a different nucleus shape. C: Giardia lamblia - This is not the correct answer as Giardia lamblia is a flagellated protozoa with a pear-shaped nucleus, different from the description provided. D: Trichomonas hominis - This is not the correct answer as Trichomonas hominis is a flagellated protozoa with multiple flagella and an undulating membrane, which does not match the characteristics of the

Correct Answer: A

Rationale: The correct answer is A: Balantidiasis. The large ciliated protozoa with a kidney-shaped macronucleus described in the stool sample is consistent with Balantidium coli, the causative agent of balantidiasis. Balantidium coli is the only ciliated protozoan parasite that infects humans and presents with these specific characteristics. Giardiasis (B) is caused by Giardia intestinalis, which is flagellated, not ciliated. Amoebiasis (C) is caused by Entamoeba histolytica, which has an amoeboid shape, not ciliated. Trichomoniasis (D) is caused by Trichomonas vaginalis, which is a flagellated protozoan and does not have a kidney-shaped macronucleus. Hence, the correct diagnosis in this case is Balantidiasis.

Correct Answer:

Rationale: Correct Answer: C: opportunists Rationale: 1. Opportunistic microorganisms cause infections only when the host's immune system is compromised. 2. They are typically harmless in healthy individuals but can become pathogenic in weakened hosts. 3. Saprophytic microorganisms are environmental decomposers, not inherently pathogenic. 4. Facultative pathogens can cause disease in both healthy and compromised hosts. 5. Obligate pathogens always cause disease regardless of the host's condition. Summary: A: Facultative pathogens can cause disease in healthy hosts. B: Saprophytes are not inherently pathogenic. D: Obligate pathogens always cause disease.