Nokea
The cell surface of pathogenic gram-negative bacteria can be covered in villi and cilia. What function do these structures have?
- A. RNA exchange between cells
- B. Inhibition of complement activity
- C. Bacterial adhesion to the surface of the host cells, conjugation
- D. Resistance to antibody opsonization
Correct Answer: C
Rationale: The correct answer is C: Bacterial adhesion to the surface of the host cells, conjugation. Villi and cilia on the cell surface of pathogenic bacteria help in bacterial adhesion to host cells, facilitating the process of infection. Conjugation is the transfer of genetic material between bacterial cells, which can be aided by these structures. The other choices are incorrect because RNA exchange between cells (A) is typically facilitated by different structures like pili, inhibition of complement activity (B) is not related to the function of villi and cilia, and resistance to antibody opsonization (D) is usually achieved through other mechanisms such as capsule formation.
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Lysozyme acts on the bacterial:
- A. cytoplasm
- B. cell wall
- C. nucleus
- D. capsule
Correct Answer: B
Rationale: The correct answer is B: cell wall. Lysozyme is an enzyme that targets the cell wall of bacteria by breaking down the peptidoglycan layer, leading to bacterial cell lysis. This action disrupts the structural integrity of the bacteria, ultimately causing their death. Choices A, C, and D are incorrect because lysozyme does not target the cytoplasm, nucleus, or capsule of bacteria. The primary function of lysozyme is to act on the cell wall, making option B the correct answer in this context.
A patient with a severe case of pneumonia had sputum stained using the Gram method. The smear revealed Gram-positive cocci arranged in pairs with a capsule. What is the most likely causative agent?
- A. Streptococcus pneumoniae
- B. Staphylococcus aureus
- C. Klebsiella pneumoniae
- D. Enterococcus faecalis
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium is a common cause of pneumonia and is characterized by being Gram-positive cocci arranged in pairs with a capsule, as described in the question. The presence of a capsule is a key characteristic of Streptococcus pneumoniae, distinguishing it from the other choices. Staphylococcus aureus (B) is a Gram-positive cocci, but it typically forms clusters, not pairs. Klebsiella pneumoniae (C) is a Gram-negative rod, not a Gram-positive cocci. Enterococcus faecalis (D) is a Gram-positive cocci, but it does not typically present with a capsule in the same way Streptococcus pneumoniae does.
Crude herbal drugs must be examined for yeast-like fungi. What agar can ensure development of these microorganisms so that associating microflora will grow very slowly or won't grow at all?
- A. Sabouraud's peptone agar
- B. Endo agar
- C. Milk-salt agar
- D. Meat infusion agar
Correct Answer: A
Rationale: The correct answer is A: Sabouraud's peptone agar. This agar is specifically designed for the isolation of yeast and molds due to its low pH and high sugar content, creating an environment conducive for their growth. Yeast-like fungi thrive in this selective medium, while inhibiting the growth of bacteria and other contaminants.
Summary:
- Sabouraud's peptone agar is ideal for cultivating yeast-like fungi.
- Endo agar is used for isolation of gram-negative bacteria, not fungi.
- Milk-salt agar is used for lactobacilli and streptococci, not fungi.
- Meat infusion agar is a general-purpose medium for cultivation of a wide range of microorganisms, not specifically for yeast-like fungi.
Methods typically used to diagnose bacterial infections of the reproductive system include:
- A. microscopic examination of discharge from infected organ and microscopic examination of urine for organisms
- B. biopsy of infected tissue and use of selective media
- C. microscopic examination of fecal sample and protein test of urine
- D. antibody agglutination test and coagulation test
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. Microscopic examination of discharge from infected organ allows direct visualization of bacteria causing the infection.
2. Microscopic examination of urine for organisms can help identify any bacteria present in the urinary tract.
3. Both methods are specific for diagnosing bacterial infections in the reproductive system.
Summary:
- Choice B is incorrect as biopsy is invasive and not typically used for diagnosing bacterial infections.
- Choice C is incorrect as fecal samples and urine protein tests are not relevant for diagnosing bacterial infections in the reproductive system.
- Choice D is incorrect as antibody agglutination and coagulation tests are not primary methods for diagnosing bacterial infections in the reproductive system.
How is detected viral multiplication in cell culture
- A. by the presence of a specific cytopathic effect
- B. by using of an immunofluorescence detection method
- C. the characteristic type of viral colonies
- D. A and B both
Correct Answer: D
Rationale: The correct answer is D (A and B both). In viral multiplication, the presence of a specific cytopathic effect (CPE) in cell culture indicates viral replication. This is detected visually through changes in cell morphology. Additionally, immunofluorescence detection methods can be used to detect viral antigens within infected cells, confirming viral multiplication. Options C is incorrect as viral colonies are not typically used to detect viral multiplication in cell culture. Option B alone is not sufficient as it only focuses on immunofluorescence detection, while option A alone may not always be specific. Therefore, the combination of A and B provides a more comprehensive and accurate detection method for viral multiplication in cell culture.