ATI RN
microbiology chapter 10 test bank Questions
Question 1 of 5
During a microscopy session, spiral-shaped bacteria with loose coils and pointed ends were observed in a blood smear. What is the most likely diagnosis?
Correct Answer: B
Rationale: The correct answer is B: Leptospirosis. Spiral-shaped bacteria with loose coils and pointed ends are characteristic of Leptospira interrogans, the causative agent of Leptospirosis. This bacterium is typically found in contaminated water or soil and can infect humans through contact with infected animals or water. Syphilis (Choice A) is caused by the spirochete Treponema pallidum, which has a more tightly coiled shape and does not typically appear loose or pointed. Relapsing fever (Choice C) is caused by Borrelia species, which are also spirochetes but do not have the loose coils and pointed ends described. Lyme disease (Choice D) is caused by Borrelia burgdorferi, which, like Relapsing fever, does not match the morphology described.
Question 2 of 5
“Animalcules†were first described by
Correct Answer: B
Rationale: The correct answer is B, Antony van Leeuwenhoek. He was the first to observe and describe "animalcules" (microorganisms) through his early microscopes. Robert Hooke (A) is known for his work with cells but did not discover animalcules. Hans Janssen (C) and John Needham (D) did not make significant contributions to the discovery of microorganisms. Leeuwenhoek's pioneering observations were crucial in the development of microbiology.
Question 3 of 5
A sputum smear from a patient with pneumonia revealed Gram-positive diplococci with pointed ends surrounded by capsules. What microorganism is most likely?
Correct Answer: A
Rationale: Step-by-step rationale: 1. Gram-positive diplococci with pointed ends indicate Streptococcus pneumoniae. 2. Presence of capsules supports the likelihood of S. pneumoniae. 3. S. pneumoniae is a common cause of pneumonia. 4. Klebsiella pneumoniae is Gram-negative and does not form diplococci. 5. Neisseria meningitidis typically causes meningitis, not pneumonia. 6. Staphylococcus aureus is Gram-positive but does not typically present as diplococci in pneumonia cases.
Question 4 of 5
A Gram-positive, spore-forming bacterium was isolated from a wound infection. The bacteria were anaerobic and produced gas. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Clostridium perfringens. This bacterium is Gram-positive, spore-forming, anaerobic, and produces gas. Clostridium perfringens is commonly associated with wound infections due to its ability to produce gas gangrene. Choice B: Bacillus anthracis is also a Gram-positive, spore-forming bacterium, but it does not typically produce gas in wound infections. Choice C: Clostridium botulinum is a spore-forming, anaerobic bacterium, but it is associated with foodborne botulism rather than wound infections. Choice D: Clostridium tetani is a spore-forming, anaerobic bacterium that causes tetanus, but it does not produce gas in wound infections.
Question 5 of 5
A patient presented with an abscess caused by Gram-positive cocci in clusters, catalase-positive and coagulase-positive. What is the causative agent?
Correct Answer: A
Rationale: Rationale: 1. Gram-positive cocci in clusters point to Staphylococcus or Micrococcus. 2. Catalase-positive eliminates Streptococcus. 3. Coagulase-positive distinguishes Staphylococcus aureus. 4. Thus, the causative agent is Staphylococcus aureus. Summary: - B: Streptococcus pyogenes is catalase-negative. - C: Enterococcus faecalis is catalase-negative. - D: Micrococcus luteus is catalase-positive but coagulase-negative.