Nokea
A patient with pulmonary tuberculosis is prescribed the most effective antituberculosis antibiotic. Name this drug:
- A. Tetracycline
- B. Furasolidone
- C. Rifampicin
- D. Bactrim (Co-trimoxazole)
Correct Answer: C
Rationale: Rifampicin is the correct answer because it is a first-line antibiotic for treating pulmonary tuberculosis. It has excellent bactericidal activity and penetrates well into lung tissues where the infection is located. Rifampicin is also known for preventing the development of resistance. Tetracycline (A) and Furasolidone (B) are not commonly used for tuberculosis treatment. Bactrim (D) is a combination of sulfamethoxazole and trimethoprim, not effective for tuberculosis treatment.
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In an agar slant, bacterial colonies that appear separate or semiconfluent are referred to as:
- A. filiform
- B. echinulate
- C. beaded
- D. effuse
Correct Answer: C
Rationale: The correct answer is C: beaded. In an agar slant, beaded colonies appear as separate or semiconfluent, forming small, round colonies with gaps between them. This term accurately describes the appearance of the colonies in this context.
A: Filiform colonies are dense and opaque with smooth edges, not separate or semiconfluent.
B: Echinulate colonies have spiny projections, not the characteristic of separate or semiconfluent growth.
D: Effuse colonies spread out extensively and lack defined borders, unlike the distinct appearance of separate or semiconfluent colonies.
Infections of Legionella pneumophila are treated with:
- A. Penicillins and cephalosporins
- B. Ethambutol and isoniazid
- C. Macrolides or fluoroquinolones
- D. Second and third generation cephalosporins
Correct Answer: C
Rationale: The correct answer is C: Macrolides or fluoroquinolones. Legionella pneumophila is a bacterium that causes Legionnaires' disease, a severe form of pneumonia. Macrolides (like azithromycin) and fluoroquinolones (like levofloxacin) are the recommended first-line treatments due to their ability to penetrate into lung tissues where Legionella infects. Penicillins and cephalosporins (choice A) are not effective against Legionella as it is intracellular and resistant to these antibiotics. Ethambutol and isoniazid (choice B) are used to treat tuberculosis, not Legionella infections. Second and third generation cephalosporins (choice D) are also not effective against Legionella. Therefore, the best choice for treating Legionella pneumophila infections is macrolides or fluoroquinolones.
Transcription of viral nucleic acid to mRNA is not needed in the case of:
- A. There is no correct answer
- B. Single strand DNA viruses
- C. Double strand DNA viruses
- D. Positive strand RNA viruses
Correct Answer: D
Rationale: The correct answer is D: Positive strand RNA viruses. These viruses have RNA genomes that can be directly translated by host ribosomes without the need for transcription. In contrast, single-strand DNA and double-strand DNA viruses require transcription to generate mRNA for translation. Choice A is incorrect as there is a correct answer. Choice B and C are incorrect because both single-strand DNA and double-strand DNA viruses require transcription for mRNA synthesis.
Which one of all the clostridia that are associated with the disease myonecrosis/gas-gangrene can produce enterotoxin and could be responsible for the development of food intoxications:
- A. Clostridium septicum
- B. Clostridium perfringens
- C. Clostridium histolyticum
- D. Clostridium novyi (oedemmateins)
Correct Answer: B
Rationale: The correct answer is B: Clostridium perfringens. This bacterium is associated with myonecrosis/gas gangrene and can produce enterotoxin causing food intoxication. Clostridium septicum (A) is associated with wound infections but not known for food intoxications. Clostridium histolyticum (C) is not typically associated with myonecrosis or food intoxications. Clostridium novyi (D) is known for causing black disease in sheep and cattle, not food intoxications.
Which bacteria is known for causing the disease cholera?
- A. Shigella dysenteriae
- B. Vibrio cholerae
- C. Salmonella enterica
- D. Clostridium perfringens
Correct Answer: B
Rationale: The correct answer is B: Vibrio cholerae. Cholera is caused by Vibrio cholerae, a gram-negative bacterium that produces a toxin leading to severe watery diarrhea. Shigella dysenteriae causes dysentery, not cholera. Salmonella enterica causes salmonellosis, not cholera. Clostridium perfringens is associated with food poisoning, not cholera. In summary, Vibrio cholerae is the correct answer because it is the specific bacterium known to cause cholera, while the other choices are associated with different diseases.