microbiology an evolving science test bank -Nurselytic

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus epidermidis. The presence of Gram-positive cocci in clusters indicates a staphylococcal species. The fact that the bacteria are catalase-positive and coagulase-negative further narrow it down to Staphylococcus epidermidis, as this species fits all the given characteristics.

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Choice B, Staphylococcus aureus, is coagulase-positive.
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Choice C, Streptococcus pyogenes, is a streptococcal species, not staphylococcal.
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Choice D, Enterococcus faecalis, is a Gram-positive cocci but is catalase-negative and not typically found in clusters.

Correct Answer: A

Rationale: The correct answer is A: Trichomonas tenax. Trichomonas tenax is a flagellated protozoan commonly found in the oral cavity and does not have a cyst stage. This organism typically inhabits the gingival crevices and can be identified in dental plaque samples. Entamoeba gingivalis (
B) is an amoeba and does not have flagella. Balantidium coli (
C) is a ciliated protozoan that infects the intestines, not the oral cavity. Giardia lamblia (
D) is a flagellated protozoan that infects the intestines and has a distinct cyst stage.
Therefore, the presence of flagellated protozoa without a cyst stage in dental plaque indicates Trichomonas tenax is likely present.

Correct Answer: A

Rationale: The correct answer is A (Escherichia coli, Gardnerella vaginalis, and Staphylococcus aureus) because they are known to commonly cause nonsexually transmitted infections of the reproductive system. Escherichia coli can cause urinary tract infections that can ascend to the reproductive system. Gardnerella vaginalis is associated with bacterial vaginosis, a common infection of the vagina. Staphylococcus aureus can cause infections in the reproductive system through various means.



Choices B, C, and D are incorrect:
B: Streptococcus faecalis, Klebsiella oxytoca, and Serratia marcescens are not commonly associated with reproductive system infections.
C: Clostridium tetani and Bacillus cereus are not typically involved in reproductive system infections.
D: Neisseria gonorrhoeae causes sexually transmitted infections, Helicobacter pylori causes gastrointestinal issues, and Pseudomonas aeruginosa is more

Correct Answer: C

Rationale: The correct answer is C because the case specifically mentions "enteropathogenic bacteria and viruses," indicating a focus on these specific microorganisms.
Choice A is too broad and includes all bacteria, which is not specified in the case.
Choice B mentions opportunistic pathogenic bacteria, which are not necessarily relevant to the case.
Choice D specifies colibacilli, which may or may not be relevant to the case, but it is not as specific as choice C which clearly matches the information provided in the case.

Correct Answer: B

Rationale: The correct answer is B because endotoxins are part of the outer membrane of gram-negative bacteria. When these bacteria undergo cell lysis, the endotoxins are released, causing harmful effects. This process does not occur during bacterial replication (choice
A), antibody production (choice
C), or formation of spores (choice
D). Bacterial replication involves the creation of new bacterial cells, not the release of endotoxins. Antibody production is the immune response to pathogens, not the direct cause of endotoxin release. Spores are dormant structures formed by some bacteria, which are not directly related to the release of endotoxins.