microbiology chapter 13 test bank

microbiology chapter 13 test bank Related

Review microbiology chapter 13 test bank related questions and content

Young man is hospitalized in pulmonology with complaints of dry cough, fatigue and suffocations. The anamnesis and the lab tests lead to pneumocystis pneumonia. The CD4+ cells are less than 200/mm3. What test you will order:

  • A. For ureaplasma urealyticum
  • B. For HIV
  • C. For Treponema pallidum
  • D. For Neisseria gonorrhoea
Correct Answer: B

Rationale: The correct answer is B: For HIV. Pneumocystis pneumonia in a young man with CD4+ cells less than 200/mm3 is highly suggestive of HIV infection. HIV weakens the immune system, leading to opportunistic infections like pneumocystis pneumonia. Testing for HIV is crucial for diagnosis and appropriate management.

Explanation for other choices:
A: Testing for ureaplasma urealyticum is not indicated in this case as the symptoms and CD4+ cell count point towards an HIV-related infection.
C: Testing for Treponema pallidum (syphilis) is not relevant in the context of a young man with pneumocystis pneumonia and low CD4+ cell count.
D: Testing for Neisseria gonorrhoea is not appropriate in this scenario as the symptoms and CD4+ cell count suggest an underlying HIV infection rather than a bacterial sexually transmitted infection.

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Microscopy of a smear from a patient with foul-smelling diarrhea revealed large ciliated protozoa with a kidney-shaped macronucleus. What is the diagnosis?

  • A. Balantidiasis
  • B. Giardiasis
  • C. Amoebiasis
  • D. Trichomoniasis
Correct Answer: A

Rationale: The correct diagnosis is A: Balantidiasis. The presence of large ciliated protozoa with a kidney-shaped macronucleus is characteristic of Balantidium coli, the causative agent of balantidiasis. The ciliated trophozoites of Balantidium coli are unique compared to the other choices. Giardiasis is caused by Giardia lamblia, which has flagella and not cilia. Amoebiasis is caused by Entamoeba histolytica, which lacks cilia. Trichomoniasis is caused by Trichomonas vaginalis, which also lacks cilia. Therefore, based on the specific morphology described, the correct diagnosis is Balantidiasis.

Which bacteria is responsible for causing cholera?

  • A. Shigella dysenteriae
  • B. Vibrio cholerae
  • C. Salmonella enterica
  • D. Clostridium perfringens
Correct Answer: B

Rationale: The correct answer is B: Vibrio cholerae. Cholera is caused by this specific bacterium due to its production of cholera toxin, leading to severe watery diarrhea. Shigella dysenteriae causes dysentery, Salmonella enterica causes salmonellosis, and Clostridium perfringens causes food poisoning, none of which present with the characteristic symptoms of cholera.

Laboratory diagnosis of rabies includes all of these except:

  • A. Looking for Negri bodies
  • B. Intracerebrally infected mice
  • C. Looking for Ernst-Babes granules
  • D. Immunofluorescence method
Correct Answer: C

Rationale: The correct answer is C: Looking for Ernst-Babes granules. Laboratory diagnosis of rabies typically involves looking for Negri bodies in the brain tissue, intracerebrally infecting mice for virus isolation, and using immunofluorescence method to detect viral antigens. Ernst-Babes granules are not associated with rabies virus and are not used in the diagnosis of rabies. Therefore, choice C is incorrect.

A patient with severe abdominal pain and vomiting had a blood culture that revealed Gram-negative rods producing gas. What is the most likely causative agent?

  • A. Escherichia coli
  • B. Salmonella enteritidis
  • C. Clostridium perfringens
  • D. Campylobacter jejuni
Correct Answer: B

Rationale: The correct answer is B: Salmonella enteritidis. In this case, the presence of Gram-negative rods producing gas in the blood culture indicates a likelihood of Salmonella infection, as it is a common cause of severe abdominal pain, vomiting, and gas production. Salmonella enteritidis is a known pathogen that can cause gastroenteritis and systemic infections. Escherichia coli (choice A) can also cause similar symptoms, but it is less likely to produce gas in blood culture. Clostridium perfringens (choice C) typically causes food poisoning with rapid onset and less likely to be isolated from blood cultures. Campylobacter jejuni (choice D) is associated with gastroenteritis but is less likely to cause systemic infections with gas-producing Gram-negative rods in blood culture.

A 9 y.o. child has been taking antibiotics on account of bronchopneumonia for a long time. There appeared pain and burning in the area of mucous membrane of his lips and tongue. Objectively: mucous membrane of lips and tongue has caseous and grey plaques that can be easily removed by a spatula leaving hyperemia foci on their spot. Microscopic examination of the plaques revealed mycelium. What is the most probable diagnosis?

  • A. Candidous cheilitis
  • B. Exfoliative cheilitis
  • C. Leukoplakia
  • D. Contactant allergic cheilitis
Correct Answer: A

Rationale: The most probable diagnosis is A: Candidous cheilitis. Candidous cheilitis is a fungal infection caused by Candida species. In this case, the presence of mycelium on the plaques indicates a fungal infection. The symptoms of pain, burning, and grey plaques that can be easily removed leaving hyperemia are typical for Candidous cheilitis. Choice B (Exfoliative cheilitis) is characterized by scaling and peeling of the lips, not plaques with mycelium. Choice C (Leukoplakia) is a precancerous condition causing white plaques that cannot be easily removed. Choice D (Contactant allergic cheilitis) is an allergic reaction causing inflammation, not fungal plaques.

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