microbiology chapter 10 test bank

Correct Answer: C

Rationale: The correct answer is C: Staphylococcus saprophyticus. The rationale is that Staphylococcus saprophyticus is the only one among the listed species that is known to be resistant to novobiocin. This resistance is due to the specific mechanism of action of novobiocin, which targets DNA gyrase, and Staphylococcus saprophyticus possesses an altered DNA gyrase enzyme that renders it resistant to the antibiotic. Staphylococcus aureus and Staphylococcus epidermidis are susceptible to novobiocin, making choices A and B incorrect. Choice D, "none of the listed," is also incorrect as Staphylococcus saprophyticus is indeed resistant to novobiocin.

Correct Answer: C

Rationale: Rabbit fever, or tularemia, is caused by Francisella tularensis. This bacterium is known to infect a wide range of animals, including rabbits. The other choices, Bartonella henselae (causes cat scratch fever), Spirillum minus (causes rat bite fever), and Yersinia pestis (causes plague) are not associated with rabbit fever. Therefore, the correct answer is C based on the specific pathogen responsible for causing tularemia.

Correct Answer: A

Rationale: 1. Gram-positive cocci in clusters suggest Staphylococcus species. 2. Catalase-positive and coagulase-positive characteristics match with Staphylococcus aureus. 3. Staphylococcus aureus is a common cause of wound infections due to its virulence factors. 4. Other choices are incorrect: B) S. epidermidis is coagulase-negative and a common contaminant, C) S. pyogenes is catalase-negative, D) Enterococcus faecalis is not typically associated with wound infections.

Correct Answer: A

Rationale: Rationale: Vibrio cholerae produces the exotoxin responsible for severe diarrhea. It causes cholera by disrupting the normal functioning of the intestines. Clostridium botulinum causes botulism, not diarrhea. Streptococcus pyogenes causes strep throat and skin infections. Salmonella enterica causes food poisoning, not severe diarrhea. Therefore, the correct answer is A.

Correct Answer: D

Rationale: The correct answer is D. Escherichia coli, Salmonella enterica, and Pseudomonas aeruginosa all produce endotoxins that can lead to septic shock. Endotoxins are components of the outer membrane of Gram-negative bacteria that can trigger a systemic inflammatory response, potentially leading to septic shock. E. coli and Salmonella are common causes of bacterial infections that can result in septic shock, while P. aeruginosa is known for causing infections in immunocompromised individuals. Therefore, since all three bacteria produce endotoxins that can lead to septic shock, the correct answer is D.Choices A, B, and C are incorrect because each of these bacteria individually produces endotoxins that can contribute to septic shock.