Microbiology Chapter 13 Test Bank

Microbiology Chapter 13 Test Bank Related

Review Microbiology Chapter 13 Test Bank related questions and content

During sanitary and bacteriological examination of air in a drugstore it was revealed that the air had high concentration of sanitary meaningful microorganisms. What microorganisms are these?

  • A. Staphylococcus aureus and hemolytic streptococcus
  • B. Diphtheritic and tuberculous bacilli
  • C. Colibacilli and blue pus bacilli
  • D. Epidermal staphylococcus and Sarcina
Correct Answer: A

Rationale: The correct answer is A: Staphylococcus aureus and hemolytic streptococcus. These microorganisms are commonly found in high concentrations during sanitary and bacteriological examination of air in a drugstore due to their prevalence in the environment. Staphylococcus aureus and hemolytic streptococcus are known to be significant pathogens that can cause various infections in humans.

Rationale:
1. Staphylococcus aureus and hemolytic streptococcus are common pathogens found in the environment and can easily contaminate air in enclosed spaces like a drugstore.
2. Both microorganisms are considered to be of sanitary significance as they can cause infections and are indicators of poor hygiene and sanitation.
3. Diphtheritic and tuberculous bacilli (Choice B) are not typically associated with air contamination in a drugstore setting.
4. Colibacilli and blue pus bacilli (Choice C) are more commonly found in fecal

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A male patient has been diagnosed with gastric ulcer. Bacteriological examination of biopsy material from the affected part of stomach revealed small colonies of gram-negative, oxide reductase-positive flexibacteria that grew on the chocolate agar on the fifth day. Which of the following microorganisms is the most likely causative agent?

  • A. Helicobacter pylori
  • B. Campilobacter jejuni
  • C. Campilobacter fetus
  • D. Mycoplasma hominis
Correct Answer: A

Rationale: The correct answer is A: Helicobacter pylori. This bacterium is the most likely causative agent of gastric ulcers. Here's the rationale:
1. Helicobacter pylori is commonly associated with gastric ulcers.
2. It is a gram-negative bacterium that grows on chocolate agar and is oxide reductase-positive.
3. The slow growth on the fifth day is characteristic of H. pylori.
4. Campylobacter jejuni and Campylobacter fetus are not typically associated with gastric ulcers.
5. Mycoplasma hominis is a bacterium that lacks a cell wall and is not commonly found in gastric ulcers.

Which of the following does NOT refer to viruses

  • A. cell-free infectious living systems
  • B. obligate intracellular parasites
  • C. they have either DNA or RNA as genetic material
  • D. they are not sensitive to interferon
Correct Answer: D

Rationale: The correct answer is D because viruses are sensitive to interferon, a natural defense mechanism of the body against viral infections. Interferon helps to inhibit viral replication.
A: Viruses are cell-free infectious particles, not living systems.
B: Viruses are obligate intracellular parasites as they require host cells to replicate.
C: Viruses can have either DNA or RNA as genetic material, which is a characteristic feature.

On a certain territory mass death of rodents was registered. It was suspected that their death might have been caused by plague. What serological reaction should be applied for quick identification of antigen of the causative agent of this epizooty?

  • A. Precipitation
  • B. Agglutination
  • C. Passive hemagglutination
  • D. Complement binding
Correct Answer: B

Rationale: The correct answer is B: Agglutination. During a suspected plague outbreak, agglutination testing is used to quickly identify the antigen of the causative agent. In this test, specific antibodies are added to a sample containing the suspected antigen. If the antigen is present, it will clump together (agglutinate) with the antibodies, indicating a positive result. This method is rapid and efficient for identifying the presence of the plague-causing agent.

Choice A: Precipitation involves the formation of a visible precipitate when antigen and antibody react, but it is not as quick or specific as agglutination for identifying the antigen in this scenario.

Choice C: Passive hemagglutination is a variation of agglutination that uses red blood cells as carriers for antigens or antibodies. While it can be useful in certain situations, it is not typically the first choice for rapid identification of plague antigen.

Choice D: Complement binding is a different type of

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.

The most important virulence factor of Neisseria meningitidis is:

  • A. Exotoxin
  • B. Polysaccharide capsule
  • C. Beta-lactamase
  • D. Pyrogenic toxin
Correct Answer: B

Rationale: The correct answer is B: Polysaccharide capsule. The capsule of Neisseria meningitidis is crucial for its virulence as it helps the bacteria evade the host immune system by inhibiting phagocytosis. This allows the bacteria to survive and multiply in the host, leading to invasive infections. Exotoxins, beta-lactamase, and pyrogenic toxins are not the main virulence factors of Neisseria meningitidis and do not play as significant a role in its pathogenicity as the polysaccharide capsule.

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