medical microbiology test bank

Correct Answer: C

Rationale: Step 1: Define sexually transmitted infections (STIs) as infections primarily spread through sexual contact. Step 2: Understand that STIs can also be transmitted through non-sexual means like blood transfusions. Step 3: Recognize that choice C is incorrect as it limits STIs to only sexually transmitted infections. Step 4: Therefore, the correct answer is C as it does not encompass all possible modes of transmission for STIs. Summary: Choices A, B, and D are incorrect as they all accurately describe the characteristics of sexually transmitted infections, while choice C is incorrect as it excludes other potential modes of transmission for STIs.

Correct Answer: D

Rationale: The correct answer is D because fungi do not form flagella. Fungi reproduce sexually and asexually (A) through spores, have a cell wall (B) made of chitin, and are mostly aerobic or facultative anaerobes (C). Flagella are structures found in some protozoa and bacteria, not in fungi. Therefore, option D is the only statement that is not true about fungi.

Correct Answer: D

Rationale: The correct answer is D: tinea pedis. Athlete's foot is a fungal infection that affects the feet, specifically the skin between the toes and on the soles. "Tinea pedis" is the medical term for athlete's foot, with "tinea" meaning a fungal infection and "pedis" referring to the foot. A: tinea capitis refers to a fungal infection of the scalp, not the feet. B: tinea corporis refers to a fungal infection of the body, not specifically the feet. C: tinea versicolor refers to a fungal infection that causes discoloration of the skin, not typically on the feet. In summary, the other choices are incorrect because they refer to fungal infections affecting different parts of the body, whereas "tinea pedis" specifically refers to athlete's foot.

Correct Answer: D

Rationale: The correct answer is D: Index of fecal coli-forms. Fecal coli-forms are bacteria found in the intestines of warm-blooded animals, including humans. Their presence in water indicates fecal contamination, which is a common source of hepatitis A transmission. Monitoring the index of fecal coli-forms can help identify potential sources of contamination and assess the risk of disease transmission. A: Number of coli-phages - Coli-phages are viruses that infect coliform bacteria and are not directly related to fecal contamination. B: Escherichia coli index - While E. coli is a type of coliform bacteria found in the intestines of warm-blooded animals, it alone may not be a reliable indicator of fecal contamination in water sources. C: Oxidability - Oxidability is a measure of the water's ability to react with oxygen and does not provide direct information about fecal contamination or the presence of pathogens like hepatitis A. In summary,

Correct Answer: C

Rationale: The correct answer is C: Polar placement of volutin granules. This feature is indicative of Corynebacterium diphtheria. Volutin granules are metachromatic granules found in the polar region of the bacterial cell, which is characteristic of this species. This feature helps differentiate it from other bacteria. Explanation: A: Fence-like position of the agent's cells is not a specific morphologic feature of Corynebacterium diphtheria. B: Spores that exceed cells in diameter is not a characteristic feature of Corynebacterium diphtheria. D: Presence of the capsule is not a distinguishing morphologic feature of Corynebacterium diphtheria. In summary, the polar placement of volutin granules is the most indicative feature for determining the type of agent as Corynebacterium diphtheria, making it the correct choice.