Microbiology An Introduction 13th Edition Test Bank

Correct Answer: A

Rationale: The correct answer is A: Benzylpenicillin sodium salt. Benzylpenicillin is a beta-lactam antibiotic that inhibits the synthesis of bacterial cell walls by disrupting the formation of murein (peptidoglycan), leading to bacterial cell death. This mechanism specifically targets the causative agent of syphilis, Treponema pallidum. - Choice B: Bijochinol is not a known drug used to treat syphilis. - Choice C: Ciprofloxacin is a fluoroquinolone antibiotic that works by inhibiting bacterial DNA replication and is not the first-line treatment for syphilis. - Choice D: Azithromycin is a macrolide antibiotic that interferes with bacterial protein synthesis and is commonly used to treat other infections but is not the preferred treatment for syphilis.

Correct Answer: A

Rationale: The correct answer is A: iatrogenic infections. Iatrogenic infections are those caused by medical interventions like catheter use. Catheters can introduce pathogens into the body, leading to infections. Local infections (B) refer to infections confined to a specific area, not necessarily caused by catheters. Exogenous infections (C) come from an external source, not specifically related to medical interventions. Endogenous infections (D) arise from the body's own flora and are not directly related to catheter use.

Correct Answer: D

Rationale: The correct answer is D: Mycoplasma. Mycoplasma is the only bacteria among the choices that have sterols in their cytoplasmic membrane. This feature helps stabilize their membrane structure due to the lack of a cell wall. Legionella (A), Bacillus (B), and Rickettsia (C) do not contain sterols in their cytoplasmic membrane. Legionella has a unique lipid composition, Bacillus has peptidoglycan in its cell wall, and Rickettsia is an intracellular parasite lacking sterols in its membrane.

Correct Answer: C

Rationale: The correct answer is C: Carry genes for antibiotic resistance. Bacterial plasmids are small, circular DNA molecules that can be transferred between bacteria, carrying genes such as antibiotic resistance. This allows bacteria to survive in the presence of antibiotics. Plasmids do not directly play a role in protein synthesis (choice A) or DNA replication (choice B). Plasmids are not responsible for motility (choice D) as that function is usually carried out by flagella or other cellular structures.

Correct Answer: C

Rationale: Rationale: 1. The male reproductive system is considered sterile as it does not have a natural microbiota. 2. Any presence of microorganisms in this system could indicate an infection or disease. 3. Therefore, choice C, sterile with no normal flora, is the best characterization. Summary: A: Incorrect - The male reproductive system does not typically have gram-positive rods. B: Incorrect - Acid-fast rods are not part of the normal flora in the male reproductive system. D: Incorrect - The male reproductive system does not typically have gram-positive spore formers.