ATI RN
microbiology chapter 12 test bank Questions
Question 1 of 5
Which toxin is specific for ETEC:
Correct Answer: D
Rationale: The correct answer is D: LT enterotoxin. This toxin is specific for Enterotoxigenic E. coli (ETEC) and is responsible for causing diarrhea by increasing cyclic AMP levels in intestinal cells. TSST-1 (choice A) is produced by Staphylococcus aureus, not ETEC. Shiga-like toxin (choice B) is produced by Shigella and EHEC, not ETEC. Erythrogenic toxin (choice C) is produced by Streptococcus pyogenes, not ETEC. Therefore, the LT enterotoxin is the specific toxin associated with ETEC.
Question 2 of 5
When cultured on solid growth media, bacteria with long O-specific chains form:
Correct Answer: A
Rationale: The correct answer is A: Smooth S colonies. Bacteria with long O-specific chains are known as smooth strains, and when cultured on solid growth media, they form smooth colonies due to the presence of the O antigen. This gives them a glossy appearance. Rough R colonies (Choice B) lack O antigen and appear rough. Mucoid -M colonies (Choice C) are associated with capsules, not O-specific chains. H colonies (Choice D) are not relevant to the O-specific chains. Smooth S colonies are the characteristic phenotype of bacteria with long O-specific chains when cultured on solid media.
Question 3 of 5
Shigella sonnei can escape phagocytic clearance by which mechanism?
Correct Answer: A
Rationale: The correct answer is A because Shigella sonnei escapes phagocytic clearance by lysing the phagosome and replicating in the cytoplasm. This allows the bacterium to avoid being destroyed by the acidic environment and enzymes in the phagolysosome. Choice B is incorrect as Shigella does not have a capsule. Choice C is incorrect because Shigella actually induces phagosome-lysosome fusion to facilitate its escape. Choice D is incorrect as protein A is a component of Staphylococcus aureus, not Shigella sonnei.
Question 4 of 5
On the base of the clinical data a child was diagnosed with atypical pneumonia resistant to the effects of beta-lactam antibiotics. The patient's sputum was cultured and incubated in a special medium, which resulted in growth of microorganisms forming microscopic colonies with a dense center (looking like fried eggs). What microorganism caused the disease?
Correct Answer: A
Rationale: The correct answer is A: Mycoplasma pneumoniae. Mycoplasma pneumoniae is a common cause of atypical pneumonia and is known to be resistant to beta-lactam antibiotics. The description of microorganisms forming microscopic colonies with a dense center resembling fried eggs is characteristic of Mycoplasma pneumoniae colonies seen on special media. Summary of other choices: B: Klebsiella pneumoniae is not typically associated with atypical pneumonia and does not exhibit the described colony morphology. C: Streptococcus pneumoniae is not resistant to beta-lactam antibiotics and does not produce colonies with the described appearance. D: Legionella pneumophila is associated with Legionnaires' disease, not atypical pneumonia, and does not form colonies resembling fried eggs.
Question 5 of 5
Bacteria that require oxygen for survival are called:
Correct Answer: C
Rationale: The correct answer is C: Obligate aerobes. These bacteria require oxygen for their survival and growth. They utilize oxygen in their metabolic processes and cannot survive in the absence of oxygen. Choice A, obligate anaerobes, cannot survive in the presence of oxygen. Choice B, facultative anaerobes, can switch between aerobic and anaerobic metabolism based on oxygen availability. Choice D, aerotolerant anaerobes, can tolerate the presence of oxygen but do not require it for their growth. Therefore, the most appropriate term for bacteria that require oxygen for survival is obligate aerobes.