Nokea
Mycobacteria have in their cell walls:
- A. High amount of polysaccharides
- B. High amount of lipids
- C. High amount of mycolic acids
- D. High amount of proteins
Correct Answer: C
Rationale: The correct answer is C: High amount of mycolic acids. Mycobacteria are characterized by their unique cell wall composition, which includes a high amount of mycolic acids. Mycolic acids provide the bacteria with resistance to environmental stresses and are crucial for their pathogenicity. Polysaccharides (A) are not a prominent component of mycobacterial cell walls. While lipids (B) are present in mycobacterial cell walls, mycolic acids are the predominant lipid. Proteins (D) are also present but are not the defining feature of mycobacterial cell walls. Therefore, the correct answer is C due to the significant role mycolic acids play in the structure and function of mycobacterial cell walls.
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Chemically an antigen may be:
- A. Lipid
- B. Protein
- C. Polysaccharide
- D. Any of these
Correct Answer: D
Rationale: The correct answer is D because antigens can be composed of lipids, proteins, or polysaccharides. Antigens are molecules that can elicit an immune response in the body. They can be diverse in their chemical composition, leading to the recognition and response by the immune system. Therefore, the correct choice is D as antigens can be any of these chemical components. Choices A, B, and C are incorrect because they each represent a possible chemical composition of antigens, but the flexibility of antigens to be made up of any of these components makes D the most accurate choice.
Specimen of a patient's sputum was stained with the following dyes and reagents: Ziehl's solution, methylene blue solution, 5% solutoin of sulfuric acid. What staining method was applied?
- A. Ziehl-Neelsen
- B. Burri's
- C. Gram's
- D. Peshkov's
Correct Answer: A
Rationale: The correct answer is A: Ziehl-Neelsen staining method was applied.
1. Ziehl's solution is used as a primary stain in Ziehl-Neelsen staining for acid-fast organisms like Mycobacterium tuberculosis.
2. Sulfuric acid is used as a decolorizer to remove excess stain.
3. Methylene blue is not part of the Ziehl-Neelsen staining method.
4. Burri's, Gram's, and Peshkov's staining methods are not used for acid-fast staining.
The most common causative agent of nosocomial infections are:
- A. E.Coli, S. aureus, L. monocytogenes
- B. E. Coli, S. aureus, Enterobacteriacae
- C. S. epidermidis, E.Coli, Enterococcus spp.
- D. None of the above
Correct Answer: C
Rationale: Rationale: Choice C is correct because Staphylococcus epidermidis, Escherichia coli, and Enterococcus spp. are common causative agents of nosocomial infections due to their presence on the skin, in the gut, and in healthcare settings. S. aureus and L. monocytogenes (Choice A) are also important pathogens but are less common in nosocomial infections. Enterobacteriaceae (Choice B) are a large family of bacteria that can cause infections but are not as commonly associated with nosocomial infections compared to the organisms in Choice C. The correct answer (Choice C) encompasses pathogens commonly found in healthcare settings, making it the most suitable option.
Which of the following viruses can cause hemorrhagic cystitis in immunocompromised patients:
- A. EBV
- B. BKV
- C. HSV1
- D. JCV
Correct Answer: B
Rationale: The correct answer is B: BKV. BK virus can cause hemorrhagic cystitis in immunocompromised patients by infecting the urinary tract. It primarily affects the renal tubular epithelial cells, leading to hemorrhagic cystitis. EBV (A) causes infectious mononucleosis, HSV1 (C) causes oral and genital herpes, and JCV (D) causes progressive multifocal leukoencephalopathy, none of which are associated with hemorrhagic cystitis.
Viral capsomeres are composed of subunits called
- A. envelopes.
- B. protomeres.
- C. capsids.
- D. nucleoids.
Correct Answer: B
Rationale: The correct answer is B: protomeres. Viral capsomeres are the building blocks of viral capsids, which are protein coats that enclose and protect the viral genetic material. These capsomeres are made up of smaller subunits called protomeres. Envelopes (A) refer to a lipid membrane surrounding some viruses, not the subunits of capsomeres. Capsids (C) are the protein coats that capsomeres make up, not the subunits themselves. Nucleoids (D) are found in bacterial cells and refer to the region where the genetic material is located, not the subunits of viral capsomeres.