In-vitro selection of resistance of Staphylococcus aureus to teicoplanin and vancomycin.
Nineteen strains of Staphylococcus aureus (five penicillin-susceptible and methicillin-susceptible, four methicillin-susceptible and penicillin-resistant, and ten methicillin-resistant) were serially subcultured in broth media containing a subinhibitory concentration (half the MIC) of either teicoplanin or vancomycin. The MIC of the antibiotic was again measured after five passages in antibiotic-containing broth. The experiment was terminated after 25 passages. After passage fifteen strains exhibited an eight-fold or greater increase in MIC of teicoplanin. On the other hand, only two strains exhibited even an unstable four-fold increase in MIC of vancomycin.
Watanakunakorn
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Department of Internal Medicine, St. Elizabeth Hospital Medical Center, Youngstown, Ohio 44501.
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D006020:Glycopeptides / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000187:drug effects*; D017334:Teicoplanin; D014640:Vancomycin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D006020:Glycopeptides; D017334:Teicoplanin; D014640:Vancomycin