openstax microbiology test bank

Correct Answer: B

Rationale: The correct answer is B, Clostridium botulinum. This bacterium is capable of forming spores, which are dormant, resistant structures that help bacteria survive harsh conditions. Staphylococcus aureus (A), Escherichia coli (C), and Neisseria gonorrhoeae (D) do not form spores. Staphylococcus aureus is a gram-positive bacterium that does not produce spores. Escherichia coli is a gram-negative bacterium that also does not form spores. Neisseria gonorrhoeae is a gram-negative bacterium and does not have the ability to form spores. Therefore, the only bacteria among the options that can form spores is Clostridium botulinum.

Correct Answer: B

Rationale: The correct answer is B because lysozyme, lactoferrin, interferon, and complement are all humoral factors involved in natural resistance. Lysozyme and lactoferrin are antimicrobial proteins that help defend against pathogens. Interferon is a signaling protein that inhibits viral replication, while complement is a group of proteins that enhance the immune response by promoting inflammation and opsonization. Choices A, C, and D are incorrect: - Choice A mentions only macrophages, which are not humoral factors but rather phagocytic cells. - Choice C lists immune cells involved in adaptive immunity (B and T lymphocytes, NK cells) rather than humoral factors of natural resistance. - Choice D includes immunoglobulins, which are part of adaptive immunity, not natural resistance.

Correct Answer: C

Rationale: The correct answer is C: phialospores. Phialospores are conidiospores that bud off from a vase-shaped spore-bearing cell called a phialide. This structure is characteristic of fungi in the genus Penicillium. Arthrospores (A) are formed by the fragmentation of hyphae, porospores (B) are not a recognized term in mycology, and blastospores (D) are produced by budding from yeast cells. Therefore, C is the correct choice based on the specific description provided in the question.

Correct Answer: B

Rationale: The correct answer is B: Phage typing of the obtained culture. This method is used for typing Mycobacterium tuberculosis strains based on susceptibility to specific bacteriophages. If the culture shows susceptibility, it confirms the presence of M. tuberculosis. In this case, the absence of cord factor indicates that the bacteria are unlikely to be M. tuberculosis. Option A (Inoculation of laboratory animals) is unethical and not necessary when other methods are available. Option C (Allergy skin test) is not relevant for confirming a diagnosis of renal tuberculosis. Option D (Toxigenicity testing) is not specific for confirming or refuting a diagnosis of M. tuberculosis.

Correct Answer: B

Rationale: The correct answer is B: Ethambutol. Ethambutol is known to cause optic neuritis, affecting the visual nerve. It is a well-documented side effect of this drug. Isoniazid (Choice A) is associated with peripheral neuropathy, not optic neuritis. Kanamycin (Choice C) is known for its side effects on the inner ear, causing hearing loss. Rifampicin (Choice D) is not typically associated with optic neuritis but can cause other adverse effects like hepatitis. By process of elimination and knowledge of drug side effects, Ethambutol is the most likely culprit.