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Pharmacology · single question

Clindamycin does NOT effectively treat which bacterium?

  1. Peptostreptococcus species
  2. Bacteroides fragilis
  3. Streptococcus viridans
  4. Pseudomonas aeruginosa
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Correct answer: D. Pseudomonas aeruginosa

  • A. Incorrect — clindamycin IS effective against Peptostreptococcus (anaerobic gram-positive cocci).
  • B. Incorrect — clindamycin IS effective against Bacteroides fragilis (anaerobic gram-negative rod).
  • C. Incorrect — clindamycin IS effective against Streptococcus viridans.
  • D. Correct. PSEUDOMONAS AERUGINOSA is an aerobic gram-negative rod that is INTRINSICALLY RESISTANT to clindamycin. Clindamycin covers mostly gram-positive aerobes and anaerobes — it has NO activity against Pseudomonas or most aerobic gram-negative rods.

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