foundations in microbiology test bank

foundations in microbiology test bank Related

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Erysipelas is a bacterial infection characterised by well-defined areas of bright-red, inflamed and rough or leathery skin. Which one is the causative agent:

  • A. Pseudomonas aeruginosa
  • B. Staphylococcus aureus
  • C. Streptococcus pyogenes
  • D. Candida albicans
Correct Answer: C

Rationale: Step-by-step rationale for Choice C (Streptococcus pyogenes) being the correct answer:
1. Erysipelas is a skin infection characterized by well-defined red, inflamed skin areas.
2. Streptococcus pyogenes is a common causative agent of erysipelas.
3. This bacterium produces enzymes that break down skin proteins, leading to the characteristic symptoms of erysipelas.
4. Streptococcus pyogenes is known for causing skin infections, including erysipelas.

Summary of why the other choices are incorrect:
A. Pseudomonas aeruginosa: Typically causes opportunistic infections, but not commonly associated with erysipelas.
B. Staphylococcus aureus: Can cause skin infections, but not typically associated with erysipelas.
D. Candida albicans: Fungal infection, not a bacterium, and not known to cause erysipelas.

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Poxviruses are DNA viruses that replicate in the Cytoplasm

  • A. TRUE
  • B. FALSE
  • C. Both answers can be correct depending on the given situation
  • D. None of the above
Correct Answer: A

Rationale: The correct answer is A: TRUE. Poxviruses are indeed DNA viruses that replicate in the cytoplasm. This is due to their complex structure that allows them to carry out their replication process in the cytoplasm of the host cell. Other choices are incorrect because poxviruses specifically replicate in the cytoplasm and do not require the nucleus for replication, ruling out choice B. Choice C is incorrect because poxviruses consistently replicate in the cytoplasm regardless of the situation. Choice D is incorrect as the correct answer is A.

A patient with a productive cough and fever had a sputum smear revealing Gram-positive cocci in clusters. What is the most likely causative agent?

  • A. Staphylococcus aureus
  • B. Streptococcus pneumoniae
  • C. Neisseria meningitidis
  • D. Klebsiella pneumoniae
Correct Answer: A

Rationale: The correct answer is A: Staphylococcus aureus. Staphylococcus aureus is a Gram-positive cocci bacterium that forms clusters and commonly causes pneumonia with a productive cough and fever. It is frequently found in sputum smears in such cases. Streptococcus pneumoniae (B) is another common cause of pneumonia but typically appears in pairs or chains, not clusters. Neisseria meningitidis (C) is a Gram-negative diplococcus that causes meningitis, not pneumonia. Klebsiella pneumoniae (D) is a Gram-negative bacterium that can cause pneumonia but appears as Gram-negative rods, not Gram-positive cocci in clusters.

Which of the following bacteria is known for producing a toxin that causes botulism?

  • A. Clostridium botulinum
  • B. Clostridium tetani
  • C. Staphylococcus aureus
  • D. Neisseria gonorrhoeae
Correct Answer: A

Rationale: The correct answer is A: Clostridium botulinum. This bacterium is known for producing botulinum toxin, which causes botulism. It is an anaerobic, spore-forming bacterium commonly found in soil. Clostridium tetani causes tetanus, not botulism. Staphylococcus aureus can cause food poisoning but not botulism. Neisseria gonorrhoeae is responsible for gonorrhea, not botulism. Therefore, A is the correct answer due to the specific association of Clostridium botulinum with botulism toxin production.

A patient was taken to a hospital with acute food poisoning caused by homemade canned mushrooms. The product analysis revealed some microorganisms that develop only in the absence of oxygen. What microorganisms caused the poisoning?

  • A. Obligate anaerobes
  • B. Facultative anaerobes
  • C. Microaerophiles
  • D. Obligate aerobes
Correct Answer: A

Rationale: The correct answer is A: Obligate anaerobes. These microorganisms thrive in the absence of oxygen, as seen in the canned mushrooms where oxygen is limited. They produce toxins causing food poisoning. Facultative anaerobes (B) can survive with or without oxygen. Microaerophiles (C) require low levels of oxygen. Obligate aerobes (D) need oxygen to survive and would not be responsible for the poisoning in this case.

The mold that produces penicillin is an example of:

  • A. parasitism
  • B. mutualism
  • C. commensalism
  • D. amensalism
Correct Answer: D

Rationale: The correct answer is D: amensalism. Penicillin mold produces a substance that inhibits the growth of bacteria, but it does not benefit nor harm the bacteria directly. This relationship is characterized by one organism (the mold) negatively affecting another (the bacteria) without any benefit or harm to itself. In parasitism (A), one organism benefits at the expense of another. In mutualism (B), both organisms benefit from the relationship. In commensalism (C), one organism benefits while the other is unaffected. Therefore, the mold producing penicillin fits the definition of amensalism.

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