Nokea
Gram-negative bacteria have a cell wall that:
- A. contains teichoic acid
- B. is thicker than that of Gram-positive bacteria
- C. contains lipopolysaccharides
- D. is composed entirely of peptidoglycan
Correct Answer: C
Rationale: The correct answer is C, as Gram-negative bacteria have a cell wall containing lipopolysaccharides. This outer membrane structure is unique to Gram-negative bacteria and plays a critical role in pathogenicity and immune response. Teichoic acid (choice A) is found in Gram-positive bacteria. The cell wall of Gram-negative bacteria is thinner than that of Gram-positive bacteria (choice B). The cell wall of Gram-negative bacteria is not composed entirely of peptidoglycan (choice D), as it also contains other components like lipopolysaccharides.
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Allergy to penicillin is an example of:
- A. Type I hypersensitivity reaction
- B. Type II hypersensitivity reaction
- C. Type III hypersensitivity reaction
- D. Type IV hypersensitivity reaction
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. Penicillin allergy involves IgE antibodies binding to penicillin.
2. This triggers mast cell degranulation, releasing histamine.
3. Histamine causes allergic symptoms like rash, swelling.
4. This immune response characterizes Type I hypersensitivity reactions.
Summary of other choices:
B: Type II reactions involve antibody-mediated cell destruction, not seen in penicillin allergy.
C: Type III reactions involve immune complex deposition, not typical in penicillin allergy.
D: Type IV reactions are delayed hypersensitivity reactions, not immediate like penicillin allergy.
All of the following are beta-lactam antibiotics except
- A. Benzylpenicillin
- B. Monobactam
- C. Cephalosporin
- D. Vancomycin
Correct Answer: D
Rationale: The correct answer is D, Vancomycin, because it is not a beta-lactam antibiotic. Beta-lactam antibiotics contain a beta-lactam ring in their molecular structure, which Vancomycin lacks. Benzylpenicillin, Cephalosporin, and Monobactam all contain the beta-lactam ring, making them beta-lactam antibiotics. Vancomycin belongs to a different class of antibiotics called glycopeptides.
A patient who came to the doctor because of his infertility was administered to make tests for toxoplasmosis and chronic gonorrhoea. Which reaction should be performed to reveal latent toxoplasmosis and chronic gonorrhoea in this patient?
- A. RIHA - Reverse indirect hemagglutination assay
- B. RDHA - Reverse direct hemagglutination assay
- C. IFA - Immunofluorescence assay
- D. Immunoblot analysis
Correct Answer: C
Rationale: The correct answer is C: IFA - Immunofluorescence assay. Toxoplasmosis and chronic gonorrhea can be detected using serological tests like IFA. IFA detects specific antibodies in the patient's serum by using fluorescently labeled antibodies. This method is highly sensitive and specific for detecting both acute and latent infections.
Explanation of Incorrect Choices:
A: RIHA - Reverse indirect hemagglutination assay - This test is not commonly used for detecting toxoplasmosis or chronic gonorrhea.
B: RDHA - Reverse direct hemagglutination assay - This test is not typically used for these specific infections.
D: Immunoblot analysis - While Immunoblot analysis is a useful confirmatory test for certain infections, it is not the primary method for detecting toxoplasmosis or chronic gonorrhea.
A patient has food poisoning. Laboratory analysis revealed a culture of anaerobic gram-positive spore-forming bacteria. What is the most likely kind of the isolated causative agent?
- A. C. perfringens
- B. Proteus vulgaris
- C. P. mirabilis
- D. Vibrio parahemolyticus
Correct Answer: A
Rationale: The correct answer is A: C. perfringens. This is because Clostridium perfringens is a gram-positive, anaerobic, spore-forming bacterium commonly associated with food poisoning. It produces toxins that cause gastrointestinal symptoms. Proteus vulgaris (B) and P. mirabilis (C) are gram-negative bacteria not typically associated with food poisoning. Vibrio parahemolyticus (D) is a gram-negative bacterium causing seafood-related gastroenteritis, not spore-forming or anaerobic.
Which of the following diseases is considered to fall in the group II category?
- A. Anthrax
- B. Lyme disease
- C. Mumps
- D. Smallpox
Correct Answer: C
Rationale: The correct answer is C: Mumps. Group II diseases are vaccine-preventable diseases that are communicable and can cause outbreaks. Mumps fits this criteria as it is preventable through vaccination, easily transmitted through respiratory droplets, and can lead to outbreaks in communities. Anthrax (A) is a zoonotic disease, Lyme disease (B) is transmitted by ticks, and Smallpox (D) has been eradicated.