microbiology an evolving science test bank

Correct Answer: C

Rationale: The correct answer is C: Reaction type GRUBER. Agglutination reaction in GRUBER involves the clumping of particles due to specific antibodies binding to antigens on the surface. This reaction is commonly used in blood typing and serology tests. A: Western blot is a technique used to detect specific proteins in a sample, not related to agglutination. B: ELISA is an enzyme-linked immunosorbent assay used to detect antibodies or antigens, not based on agglutination. D: Ascoli ring test is a method to detect the presence of DNA in a sample, not related to agglutination.

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: A

Rationale: The correct answer is A: Clostridium tetani. This bacterium is responsible for causing tetanus due to its production of tetanus toxin. Clostridium perfringens (B) causes gas gangrene, Streptococcus pyogenes (C) causes strep throat and skin infections, and Escherichia coli (D) is a common gut bacteria that can cause food poisoning but not tetanus.

Correct Answer: A

Rationale: The correct answer is A: Actinomycosis. This is a chronic bacterial infection caused by Actinomyces species. In this case, the description of dense yellow-green colored focus, white granules in purulent masses, and presence of fungal druses, plasma cells, xanthome cells, and macrophages all match the characteristics of actinomycosis. Actinomycosis typically presents with abscess formation containing sulfur granules, which are yellowish and granular. The other choices (B: Furuncle, C: Carbuncle, D: Syphilis) do not fit the clinical and histological features described in the question, making them incorrect options.

Correct Answer: A

Rationale: The correct answer is A: Commensalism. In this relationship, the skin microflora benefits from the host without causing harm or benefitting it. This is evident in the mutualistic interaction where the microflora receive nutrients and a place to live, while the host remains unaffected. Choice B, Infection, is incorrect because it implies harm to the host. Choice C, Parasitism, is also incorrect as it involves one organism benefiting at the expense of the other. Choice D, No correct answer, is not applicable here as Commensalism accurately describes the relationship between the macroorganism and skin microflora.