microbiology chapter 11 test bank -Nurselytic

Correct Answer: A

Rationale: The correct answer is A: Delayed-type hypersensitivity. The Mantoux test is a type IV hypersensitivity reaction, which is also known as delayed-type hypersensitivity. This reaction typically occurs 48-72 hours after exposure to an antigen, such as tuberculin in this case. The focal skin hardening and redness that appeared 60 hours after tuberculin introduction align with the timeline and characteristics of a delayed-type hypersensitivity reaction.

Summary:
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Choice A (Delayed-type hypersensitivity): Correct, as explained above.
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Choice B (Immune complex-mediated hypersensitivity): Incorrect, as this reaction involves immune complexes and typically presents with tissue damage and inflammation.
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Choice C (Complement-mediated cytotoxic hypersensitivity): Incorrect, as this reaction involves the activation of complement proteins leading to cell lysis.
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Choice D (Immediate hypersensitivity): Incorrect, as this reaction, such as in allergies, occurs within minutes to hours of exposure to an antigen and involves IgE-mediated mast

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus epidermidis. This is supported by the characteristics of Gram-positive cocci in clusters, catalase-positive, and coagulase-negative. Staphylococcus epidermidis fits all these criteria, as it is a common skin commensal that can cause infections in immunocompromised individuals. Staphylococcus aureus (choice
B) is catalase-positive and coagulase-positive. Streptococcus pyogenes (choice
C) is catalase-negative. Enterococcus faecalis (choice
D) is catalase-negative and not typically seen in clusters.
Therefore, based on the given information, Staphylococcus epidermidis is the most likely causative agent.

Correct Answer: C

Rationale:
Step-by-step rationale:
1. Shigella is a nonmotile bacterium.
2. This lack of motility is a key characteristic used to differentiate it from other enteric bacteria.
3. Nonmotile nature of Shigella helps it to cause infections by invading the intestinal epithelial cells.
4.
Therefore, choice C is correct as Shigella is indeed nonmotile.

Summary:
A: Incorrect - Shigella does not produce hydrogen sulfide.
B: Incorrect - Shigella does not ferment lactose.
D: Incorrect - Shigella is not mannitol positive.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Hospital-acquired infections can be caused by a variety of bacteria commonly found in healthcare settings. Staphylococcus aureus is a common cause of surgical site infections. Escherichia coli can cause urinary tract infections. Klebsiella pneumoniae is associated with pneumonia and bloodstream infections.
Therefore, all three bacteria are frequently implicated in hospital-acquired infections due to their prevalence and ability to cause different types of infections in healthcare settings. Thus, the correct answer is D, as all of the listed bacteria are commonly associated with hospital-acquired infections.

Correct Answer: C

Rationale: The correct answer is C: 4-10% of all materials building the cell wall. Gram (-) bacteria have a thin peptidoglycan layer making up 4-10% of the cell wall. This is in contrast to Gram (+) bacteria which have a thicker peptidoglycan layer.
Choice A is too high a percentage for Gram (-) bacteria.
Choice B is too low as it would not provide enough structural support.
Choice D is also too high and would not accurately reflect the composition of Gram (-) bacteria.