Nokea
A patient presents with a history of diarrhea of several weeks' duration. Which of the following may be the cause?
- A. Bordetella pertussis
- B. Yersinia enterocolitica
- C. Corynebacterium diphtheria
- D. Neisseria meningitidis
Correct Answer: B
Rationale: The correct answer is B: Yersinia enterocolitica. Y. enterocolitica is known to cause gastroenteritis and diarrhea in humans. It is often associated with contaminated food or water. Bordetella pertussis causes whooping cough, not diarrhea. Corynebacterium diphtheria causes respiratory diphtheria. Neisseria meningitidis is associated with meningitis and septicemia, not diarrhea. Therefore, based on the patient's symptoms and history, Y. enterocolitica is the most likely cause of the diarrhea in this case.
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Which one is an example of an immunomodulator
- A. Pentaxim
- B. Hexacima
- C. Gamma-interferon
- D. Rifampin
Correct Answer: C
Rationale: Step-by-step rationale for why C is correct:
1. Immunomodulators regulate the immune response.
2. Gamma-interferon is a cytokine that enhances immune function.
3. It helps fight infections and regulate inflammation.
4. Pentaxim and Hexacima are combination vaccines.
5. Rifampin is an antibiotic, not an immunomodulator.
Summary:
- A and B are combination vaccines.
- D is an antibiotic.
- C is the correct answer as gamma-interferon is an immunomodulator that regulates the immune response.
The incubation period for hepatitis B is:
- A. One week - 10 days
- B. One month - 45 days
- C. Up to 3 months
- D. Up to 6 months
Correct Answer: C
Rationale: The correct answer is C: Up to 3 months. Hepatitis B has an average incubation period of 60-90 days, which aligns with the timeframe of up to 3 months. This period refers to the time between exposure to the virus and the onset of symptoms. One week to 10 days (choice A) is too short for hepatitis B, as it typically takes longer to manifest. One month to 45 days (choice B) is also shorter than the average incubation period for hepatitis B. Up to 6 months (choice D) is too long for hepatitis B, as the virus typically shows symptoms within 3 months.
A patient with bacterial endocarditis had Gram-positive cocci in chains isolated from blood cultures. The organism was catalase-negative. What is the most likely causative agent?
- A. Streptococcus pyogenes
- B. Staphylococcus aureus
- C. Enterococcus faecalis
- D. Micrococcus luteus
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes. This is because Streptococcus pyogenes is a Gram-positive cocci in chains bacterium that is catalase-negative, making it the most likely causative agent in this scenario. Streptococcus pyogenes is a common pathogen causing bacterial endocarditis.
Summary of other choices:
B: Staphylococcus aureus is a Gram-positive cocci bacterium but is catalase-positive, so it is unlikely in this case.
C: Enterococcus faecalis is a Gram-positive cocci bacterium, but it is catalase-negative, which is not consistent with the given information.
D: Micrococcus luteus is a Gram-positive cocci bacterium but is catalase-positive, making it an unlikely causative agent.
Which of the following bacteria is capable of surviving in extreme heat?
- A. Escherichia coli
- B. Bacillus subtilis
- C. Staphylococcus aureus
- D. Clostridium botulinum
Correct Answer: B
Rationale: The correct answer is B: Bacillus subtilis. Bacillus subtilis is a thermophilic bacterium capable of surviving in extreme heat due to its heat-resistant spores. It forms spores when exposed to unfavorable conditions, allowing it to withstand high temperatures. Escherichia coli (A), Staphylococcus aureus (C), and Clostridium botulinum (D) are mesophilic bacteria that do not have the same heat resistance mechanisms as Bacillus subtilis, making them unable to survive in extreme heat conditions.
A patient suffers from pulmonary tuberculosis. During treatment neuritis of visual nerve arose. What drug has caused this by-effect?
- A. Isoniazid
- B. Ethambutol
- C. Kanamycin
- D. Rifampicin
Correct Answer: B
Rationale: The correct answer is B: Ethambutol. Ethambutol is known to cause optic neuritis, affecting the visual nerve. It is a well-documented side effect of this drug. Isoniazid (Choice A) is associated with peripheral neuropathy, not optic neuritis. Kanamycin (Choice C) is known for its side effects on the inner ear, causing hearing loss. Rifampicin (Choice D) is not typically associated with optic neuritis but can cause other adverse effects like hepatitis. By process of elimination and knowledge of drug side effects, Ethambutol is the most likely culprit.