Nokea
Family Retroviriade:
- A. Their capsid consists of two copies of ssRNA(-)
- B. Are with complex type of symmetry
- C. Are helical, enveloped viruses
- D. Are helical, non-enveloped viruses
Correct Answer: A
Rationale: Step-by-step rationale:
1. Family Retroviridae is known for having a single-stranded RNA genome.
2. The (-) sign indicates that the RNA strand is negative-sense.
3. Therefore, the correct answer A, "Their capsid consists of two copies of ssRNA(-)," is accurate.
Summary:
- Choice B is incorrect because Retroviridae have simple type of symmetry.
- Choice C is incorrect as Retroviridae are not enveloped viruses.
- Choice D is incorrect because Retroviridae are enveloped viruses.
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The bacterium that shows swarming on blood agar
- A. providencia stuartii
- B. providencia rettgeri
- C. Proteus mirabilis
- D. morganella morganii
Correct Answer: C
Rationale: The correct answer is C: Proteus mirabilis. This bacterium shows swarming on blood agar due to its ability to produce flagella and exhibit rapid and coordinated movement. Providencia stuartii and Providencia rettgeri are not known for swarming behavior on blood agar. Morganella morganii can exhibit swarming motility, but it is not as commonly associated with this characteristic compared to Proteus mirabilis, making C the most appropriate choice.
Each of the following statements about Neisseria meningitidis is correct, EXCEPT
- A. during meningococcemia Waterhouse-Friderichsen syndrome may be present
- B. Disease is most common in children younger than age 5
- C. There is an obligatory vaccine in Bulgaria
- D. infection is transmitted by respiratory secretions in close contacts
Correct Answer: C
Rationale: The correct answer is C because there is no obligatory vaccine for Neisseria meningitidis in Bulgaria. The rationale for this is that while vaccines are available for meningococcal disease, they are not mandatory in Bulgaria. Therefore, this statement is incorrect.
A: This statement is correct as Waterhouse-Friderichsen syndrome can occur during meningococcemia due to rapid progression of the infection leading to adrenal gland failure.
B: This statement is incorrect as Neisseria meningitidis is most common in infants, children, and adolescents, with a second peak in young adults.
D: This statement is correct as Neisseria meningitidis is transmitted through respiratory secretions, such as coughing or kissing, especially in close contacts like household members or roommates.
Complement fixation test
- A. Is done in three stages
- B. Is a test that can be used to detect the presence of either specific antibody or specific antigen in a patient's serum
- C. Is done with human, not standardized complement proteins
- D. Can be made with or without sheep red blood cells
Correct Answer: B
Rationale: The correct answer is B because the complement fixation test is a serological test that detects the presence of specific antibodies or antigens in a patient's serum. It works by measuring the ability of antibodies to fix complement proteins. Choice A is incorrect because the complement fixation test typically involves several steps, not necessarily three. Choice C is incorrect as standardized complement proteins are commonly used in this test. Choice D is incorrect because sheep red blood cells are not essential for performing the complement fixation test.
Which of the following does NOT describe Cephalosporins
- A. relatively broad spectrum
- B. bactericidal
- C. beta-lactam
- D. interferes with protein synthesis
Correct Answer: D
Rationale: The correct answer is D: interferes with protein synthesis. Cephalosporins are beta-lactam antibiotics that work by inhibiting bacterial cell wall synthesis, not protein synthesis. They are bactericidal and have a relatively broad spectrum of activity against various bacteria. Choice A, B, and C all describe characteristics of cephalosporins, making them incorrect options.
A wound infection culture revealed Gram-positive cocci in clusters. The bacteria were catalase-positive and coagulase-negative. What is the most likely causative agent?
- A. Staphylococcus epidermidis
- B. Staphylococcus aureus
- C. Streptococcus pyogenes
- D. Enterococcus faecalis
Correct Answer: A
Rationale: The most likely causative agent in this case is Staphylococcus epidermidis. This conclusion can be drawn based on the characteristics provided: Gram-positive cocci in clusters, catalase-positive, and coagulase-negative. Staphylococcus epidermidis fits all these criteria.
Explanation of other choices:
- Staphylococcus aureus: Typically coagulase-positive, so it does not match the characteristics given.
- Streptococcus pyogenes: Gram-positive cocci in chains, not clusters. Also, it is catalase-negative.
- Enterococcus faecalis: Gram-positive cocci in pairs or chains, not clusters. Additionally, it is catalase-negative.
Therefore, Staphylococcus epidermidis is the most likely causative agent based on the provided characteristics.