A woman with pelvic inflammatory disease yields Mycoplasma hominis from a cervical swab. Which antimicrobial is predictably INEFFECTIVE against this organism regardless of susceptibility testing?
- A Clindamycin
- B Erythromycin ✓
- C Tetracycline
- D Fluoroquinolone
Correct answer: B. Erythromycin
Explanation
Mycoplasma hominis is inherently resistant to macrolides such as erythromycin, a property that distinguishes it from M. pneumoniae, which is macrolide susceptible. It remains generally susceptible to tetracyclines, clindamycin, and fluoroquinolones, so these are acceptable alternatives when tetracycline resistance is present. This intrinsic macrolide resistance is a favourite examination point because students assume all mycoplasmas respond to macrolides.
Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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