microbiology an evolving science test bank

Correct Answer: B

Rationale: The correct answer is B: Penicillin. Penicillin is the drug of first choice for treating syphilis due to its effectiveness in eradicating the bacterium Treponema pallidum, which causes syphilis. It is the most reliable treatment with well-established efficacy. Gentamicin (A), ciprofloxacin (C), and chloramphenicol (D) are not recommended for treating syphilis as they are not effective against the specific bacteria causing the infection. Penicillin remains the gold standard for syphilis treatment.

Correct Answer: A

Rationale: The correct answer is A because Klebsiella species have a real capsule, which is a distinguishing feature used for their identification. This capsule helps them evade the host immune response. Additionally, Klebsiella species are non-motile, meaning they do not possess flagella for movement. Choices B and C are incorrect because Klebsiella species are facultative anaerobes and do not form spores under any conditions. Choice D is also incorrect as option A is the correct statement for genus Klebsiella.

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus epidermidis. The presence of Gram-positive cocci in clusters indicates a staphylococcal species. The fact that the bacteria are catalase-positive and coagulase-negative further narrow it down to Staphylococcus epidermidis, as this species fits all the given characteristics. - Choice B, Staphylococcus aureus, is coagulase-positive. - Choice C, Streptococcus pyogenes, is a streptococcal species, not staphylococcal. - Choice D, Enterococcus faecalis, is a Gram-positive cocci but is catalase-negative and not typically found in clusters.

Correct Answer: D

Rationale: Step 1: The symptoms of optic nerve neuritis, memory impairment, and cramps are indicative of ethambutol toxicity. Step 2: Ethambutol is known to cause optic nerve toxicity leading to neuritis, as well as CNS toxicity causing memory impairment. Step 3: Ethambutol can also lead to peripheral neuropathy manifesting as cramps. Step 4: Isoniazid is associated with peripheral neuropathy and hepatotoxicity but not with optic nerve neuritis or memory impairment. Step 5: PASA is not commonly used for tuberculosis treatment and does not cause the described symptoms. Step 6: Rifampicin is known for hepatotoxicity and flu-like symptoms, but not specifically for optic nerve neuritis, memory impairment, or cramps. Summary: Ethambutol is the correct answer due to its known side effects of optic nerve toxicity, CNS toxicity, and peripheral neuropathy, which align with the presented symptoms. Ison

Correct Answer: D

Rationale: The correct answer is D: all of them. Malignant disease weakens the immune system, making individuals more susceptible to infections. Cytostatic therapy suppresses the immune system, increasing the risk of infections. Premature birth can lead to underdeveloped immune systems, making babies more prone to infections. Therefore, all three choices are risk factors for the development of infections. Other choices are incorrect because each individual risk factor listed contributes to an increased susceptibility to infections.