Microbiology Chapter 13 Test Bank

Microbiology Chapter 13 Test Bank Related

Review Microbiology Chapter 13 Test Bank related questions and content

While studying a microslide obtained from the punctuate of a regional lymph node and stained by Romanovsky-Giemsa method a physician revealed some light pink thin microorganisms with 12-14 regular spiral coils and pointed ends, up to 10-13 micrometer long. This might be the causative agent of the following disease:

  • A. Syphilis
  • B. Trypanosomiasis
  • C. Leptospirosis
  • D. Relapsing fever
Correct Answer: D

Rationale: The correct answer is D: Relapsing fever. The description matches Borrelia species, the causative agent of relapsing fever. The thin, spiral-shaped microorganisms with pointed ends and specific length are characteristic of Borrelia. The number of coils and size mentioned also align with Borrelia morphology. Relapsing fever is transmitted by tick bites and manifests as recurring febrile episodes.

Incorrect choices:
A: Syphilis - Syphilis is caused by Treponema pallidum, which is not spiral-shaped.
B: Trypanosomiasis - Trypanosomiasis is caused by Trypanosoma species, which are not spiral-shaped.
C: Leptospirosis - Leptospirosis is caused by Leptospira species, which are not spiral-shaped and do not match the specific description provided.

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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 cytoplasmic membrane in bacteria is composed of:

  • A. Phospholipids, glycerol and glycolipids
  • B. Lipopolysaccharides
  • C. Lipopolysaccharides and peptidoglycan
  • D. None of the above
Correct Answer: A

Rationale: The correct answer is A because the cytoplasmic membrane in bacteria is primarily composed of phospholipids, glycerol, and glycolipids. Phospholipids form the basic structure of the membrane, with glycerol serving as the backbone and glycolipids present on the outer surface. Lipopolysaccharides (choice B) are primarily found in the outer membrane of Gram-negative bacteria, not the cytoplasmic membrane. Choice C is incorrect because peptidoglycan is a component of the bacterial cell wall, not the cytoplasmic membrane. Choice D is incorrect as the cytoplasmic membrane in bacteria is indeed composed of phospholipids, glycerol, and glycolipids.

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.

A 16-year-old adolescent was vaccinated with DTP. In eight days there was stiffness and pain in the joints, subfebrile temperature, urticarial skin eruption, enlargement of inguinal, cervical lymph nodes and spleen. What kind of allergic reaction is observed?

  • A. Immunocomplex
  • B. Hypersensitivity of immediate type
  • C. Cytoxic
  • D. Hypersensitivity of delayed type
Correct Answer: D

Rationale: The correct answer is D: Hypersensitivity of delayed type. The symptoms described occur 5-10 days after exposure to the antigen, consistent with a delayed hypersensitivity reaction. This type of reaction involves T cells and is characterized by cell-mediated immune response, leading to inflammation and tissue damage. Choices A, B, and C are incorrect because they are associated with different mechanisms of allergic reactions. Immunocomplex reactions (choice A) involve antigen-antibody complexes depositing in tissues, immediate hypersensitivity reactions (choice B) involve IgE-mediated mast cell degranulation, and cytotoxic reactions (choice C) involve antibodies targeting specific cells for destruction.

For isolating Rickettsia, the sample is investigated via:

  • A. Skin-allergy tests
  • B. Serological methods for proving Ab
  • C. Chick embryos, cell cultures, and lab animals
  • D. None of the above
Correct Answer: C

Rationale: The correct answer is C because Rickettsia requires living cells for growth and replication. Chick embryos, cell cultures, and lab animals provide a suitable environment for Rickettsia isolation. Skin-allergy tests (A) and serological methods for proving antibodies (B) are not directly used for isolating Rickettsia as they do not support the growth of the bacteria. "None of the above" (D) is incorrect as option C involves the appropriate methods for isolating Rickettsia.

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