Capsuliferous bacteria has been detected during microbiological inspection of crude drugs. What method of staining has been used to detect capsules?

Correct Answer: A

Rationale: The correct answer is A: Burri-Gins. This staining method specifically targets the detection of capsules in bacteria. It involves staining the capsules with crystal violet and the background with safranin. This staining technique helps visualize the capsules as a distinct halo around the bacteria. Summary: - Choice B (Ziehl-Neelsen) is used for acid-fast staining to detect Mycobacterium species. - Choice C (Neisser) is used for staining Neisseria species. - Choice D (Gram) is a common staining method used to differentiate bacteria based on cell wall composition (Gram-positive and Gram-negative), but it does not specifically target capsules.

Correct Answer: C

Rationale: The correct answer is C: Reaction type GRUBER. Agglutination reaction in GRUBER involves the clumping of particles due to specific antibodies binding to antigens on the surface. This reaction is commonly used in blood typing and serology tests. A: Western blot is a technique used to detect specific proteins in a sample, not related to agglutination. B: ELISA is an enzyme-linked immunosorbent assay used to detect antibodies or antigens, not based on agglutination. D: Ascoli ring test is a method to detect the presence of DNA in a sample, not related to agglutination.

Correct Answer: C

Rationale: Chitin is a polysaccharide found in the cell walls of fungi. Bacteria have cell walls made of peptidoglycan, not chitin. Viruses do not have cell walls as they are acellular entities. Therefore, the correct answer is A: fungi.

Correct Answer: B

Rationale: The correct answer is B: Adhesion. Pili are bacterial appendages that help bacteria adhere to surfaces. This is important for colonization and biofilm formation. Choice A (Chemotaxis) is incorrect because chemotaxis is the movement of bacteria in response to chemical stimuli, not the function of pili. Choice C (Nutrient acquisition) is incorrect because pili are not directly involved in obtaining nutrients. Choice D (None of the above) is incorrect as pili do serve a specific purpose, which is adhesion.

Correct Answer: C

Rationale: The correct answer is C (7.2-7.4) because most pathogenic bacteria and viruses thrive in a neutral pH environment close to 7.0. This pH range is optimal for their growth and survival. Choice A (5.0-5.5) is too acidic for most pathogens. Choice B (8.0-9.6) is too alkaline, which is not conducive for their survival. Choice D (4.2-4.4) is also too acidic and would likely inhibit the growth of pathogenic bacteria and viruses. Thus, a pH range of 7.2-7.4 provides the most suitable conditions for their proliferation.

Correct Answer: D

Rationale: The correct answer is D: complex. Bacteriophages are considered complex viruses because they have a complex structure consisting of a polyhedral head, a helical tail, and tail fibers. The head contains the viral genetic material, while the tail facilitates attachment to the host bacterial cell. This complexity distinguishes bacteriophages from simpler viruses like helical and icosahedral viruses. Helical viruses have a rod-like shape, while icosahedral viruses have a symmetrical, 20-sided structure. Enveloped viruses have a lipid bilayer envelope surrounding their capsid, which bacteriophages lack. Therefore, the unique and intricate structure of bacteriophages classifies them as complex viruses.

Correct Answer: C

Rationale: The correct answer is C: Microaerophiles. These bacteria grow best in environments with low oxygen levels. They require oxygen for respiration but at lower concentrations than what is present in the atmosphere. This allows them to thrive in conditions where oxygen is limited but not completely absent. A: Facultative anaerobes can grow in both the presence and absence of oxygen. B: Obligate aerobes require oxygen for growth. D: Obligate anaerobes cannot survive in the presence of oxygen and typically grow in anaerobic environments. In summary, microaerophiles are the correct choice as they specifically thrive in low oxygen environments, distinguishing them from the other options.

Correct Answer: D

Rationale: The correct answer is D because all three bacteria (Salmonella enterica, Escherichia coli, Pseudomonas aeruginosa) are known to produce endotoxins, specifically lipopolysaccharides in their cell walls. Endotoxins are released upon bacterial cell death and can trigger an immune response, leading to septic shock. Salmonella and E. coli are common causes of bacterial infections, while Pseudomonas is associated with nosocomial infections. Therefore, all of the above choices are correct in terms of producing endotoxins that can cause septic shock. Choices A, B, and C are incorrect individually because they do not encompass all the bacteria known to produce endotoxins that can lead to septic shock.

Correct Answer: D

Rationale: The correct answer is D: TCBS. Thiosulfate-citrate-bile salts-sucrose (TCBS) agar is the most selective for Vibrio cholerae due to its high salt content, bile salts, and sucrose. Vibrio cholerae can grow well in alkaline conditions, which are provided by TCBS agar. MacConkey's agar (A) is selective for gram-negative bacteria, but not specifically for Vibrio cholerae. Chocolate agar (B) is a non-selective medium suitable for fastidious organisms. SS agar (C) is selective for Salmonella and Shigella species, not Vibrio cholerae.