Nokea
A patient being treated in the burns department has suppurative complication. The pus is of bluish- green color that is indicative of infection caused by Pseudomonas aeruginosa. What factor is typical for this causative agent?
- A. Gram-negative stain
- B. Presense of spores
- C. Coccal form
- D. Cell pairing
Correct Answer: A
Rationale: The correct answer is A: Gram-negative stain. Pseudomonas aeruginosa is a gram-negative bacterium, as indicated by the bluish-green pus color. This bacterium has an outer membrane that retains the crystal violet stain, making it appear pink/red after the counterstain with safranin in Gram staining. The other choices are incorrect because Pseudomonas aeruginosa does not typically form spores (B), has a rod-shaped morphology rather than a coccal form (C), and does not exhibit cell pairing (D).
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Drug of first choice for the treatment of syphilis is:
- A. Gentamicin
- B. Penicillin
- C. Ciprofloxacin
- D. Chloramphenicol
Correct Answer: B
Rationale: The correct answer is B: Penicillin. Penicillin is the drug of first choice for treating syphilis due to its effectiveness in eradicating the bacterium Treponema pallidum, which causes syphilis. It is the most reliable treatment with well-established efficacy. Gentamicin (A), ciprofloxacin (C), and chloramphenicol (D) are not recommended for treating syphilis as they are not effective against the specific bacteria causing the infection. Penicillin remains the gold standard for syphilis treatment.
Microscopy of stained (Ziehl-Neelsen staining) smears taken from the sputum of a patient with chronic pulmonary disease revealed red bacilli. What property of tuberculous bacillus was shown up?
- A. Acid resistance
- B. Alkali resistance
- C. Alcohol resistance
- D. Capsule formation
Correct Answer: A
Rationale: The correct answer is A: Acid resistance. Tuberculous bacilli are acid-fast bacilli, meaning they resist decolorization by acid-alcohol after staining with Ziehl-Neelsen stain. This property is due to the high lipid content in the cell wall of Mycobacterium tuberculosis. Alkali resistance (B) and alcohol resistance (C) are not specific properties of tuberculous bacilli. Capsule formation (D) is a characteristic of some bacteria but is not a defining feature of tuberculous bacilli.
Protein A is located in the cell wall of:
- A. Coagulase negative staphylococcus
- B. Staphylococcus aureus
- C. Micrococcus
- D. None of them
Correct Answer: B
Rationale: Protein A is a virulence factor specific to Staphylococcus aureus. This protein binds to the Fc region of immunoglobulins, inhibiting opsonization and phagocytosis. Therefore, the correct answer is B. Coagulase negative staphylococcus (choice A) does not produce Protein A. Micrococcus (choice C) is a different genus and does not possess Protein A. Choice D is incorrect because Protein A is indeed found in Staphylococcus aureus.
Which of the following bacteria can cause meningitis?
- A. Neisseria meningitidis
- B. Haemophilus influenzae
- C. Streptococcus pneumoniae
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae are all bacteria known to cause meningitis. Neisseria meningitidis is a common cause of bacterial meningitis in young adults, Haemophilus influenzae type b is a common cause in children, and Streptococcus pneumoniae is a leading cause in adults and the elderly. Therefore, all three bacteria can potentially cause meningitis depending on the age group and other factors. The other choices are incorrect because each of the bacteria listed can cause meningitis, so selecting only one of them would be incorrect.
What microorganisms were accounted for in this case?
- A. All bacteria that have grown on a nutrient medium
- B. Opportunistic pathogenic bacteria
- C. Enteropathogenic bacteria and viruses
- D. Colibacilli
Correct Answer: C
Rationale: The correct answer is C because the case specifically mentions "enteropathogenic bacteria and viruses," indicating a focus on these specific microorganisms. Choice A is too broad and includes all bacteria, which is not specified in the case. Choice B mentions opportunistic pathogenic bacteria, which are not necessarily relevant to the case. Choice D specifies colibacilli, which may or may not be relevant to the case, but it is not as specific as choice C which clearly matches the information provided in the case.