medical microbiology test bank

Correct Answer: C

Rationale: The correct answer is C: ensure survival under harsh conditions. Bacterial endospores are dormant, resistant structures that form under adverse conditions to protect the bacterial DNA and allow the bacterium to survive extreme environments. This function is crucial for the bacterium's long-term survival. Choice A is incorrect as endospores do not directly produce exotoxins. Choice B is incorrect as endospores do not store nutrients but rather protect the bacterium's genetic material. Choice D is incorrect as endospores do not enhance motility but rather enable survival during unfavorable conditions.

Correct Answer: D

Rationale: The correct answer is D: Chlamydia trachomatis. Lymphogranuloma venereum (LGV) is caused by Chlamydia trachomatis serovars L1, L2, and L3. These serovars infect the lymphatic system leading to swelling and inflammation. Choice A, Chlamydia pneumoniae, is associated with respiratory infections, not LGV. Choice B, Chlamydia psittaci, causes psittacosis in birds and humans. Choice C, Mycoplasma genitalium, is a separate STI but is not the causative agent for LGV. The key to the correct answer is understanding the specific pathogen responsible for LGV based on its clinical presentation and mode of transmission.

Correct Answer: A

Rationale: The correct answer is A: Wasserman test, IFT. The patient's symptoms of diffuse alopecia and Pinkus' sign are suggestive of secondary syphilis. The Wasserman test and Immunofluorescence Test (IFT) are used to detect antibodies against Treponema pallidum, the bacterium causing syphilis. This would confirm or rule out syphilis as the underlying cause of the patient's symptoms. Choice B (T.pallidum Immobilization Test) is similar to the Wasserman test but less commonly used. Choice C (Detection of the nasal mucous membrane for M.leprae) is irrelevant as leprosy does not present with the described symptoms. Choice D (Consultation of neuropathist) is premature without ruling out syphilis first. Thus, the Wasserman test, IFT should be the initial examination to investigate the likely cause of the patient's symptoms.

Correct Answer: D

Rationale: The correct answer is D, "All of the above," because all three bacteria (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) can cause urinary tract infections. E. coli is the most common causative agent of UTIs, followed by Staphylococcus aureus and occasionally Pseudomonas aeruginosa. Each of these bacteria has different virulence factors that enable them to infect the urinary tract. Therefore, it is important to consider all three options when diagnosing and treating UTIs. Choices A, B, and C are incorrect because each of those bacteria can individually cause UTIs, so the correct answer is D, as it encompasses all the possible causative agents.

Correct Answer: D

Rationale: The correct answer is D: decimal reduction time. This term represents the time required at a specific temperature to kill 90% of a bacterial population. It is a key parameter in microbiology to determine the effectiveness of a given heat treatment. Generation time (A) refers to the time it takes for a population to double in size. Thermal death time (B) is the shortest time needed to kill all organisms at a specific temperature. Sterilization time (C) is a general term and does not specifically refer to the time required to kill 90% of the population.