A comparative in-vitro evaluation of resistance selection after exposure to teicoplanin, vancomycin, linezolid and quinupristin-dalfopristin in Staphylococcus aureus and Enterococcus spp.
The ability of breakpoint and serum concentrations of teicoplanin, vancomycin, linezolid and quinupristin-dalfopristin to select resistance was compared for isolates of methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), Enterococcus faecalis and Enterococcus faecium. Mutation frequencies were always <10(-10), except for two isolates grown in the presence of teicoplanin at the trough serum concentration. After multistep selection, linezolid selected for resistance in staphylococci and enterococci, and serial exposure to certain concentrations of linezolid was more likely to select for stable resistance in MRSA, MSSA and enterococci than was exposure to glycopeptides and quinupristin-dalfopristin.
Drago
L
L
Laboratory of Clinical Microbiology, Department of Preclinical Science, LITA Vialba, University of Milan, Milan, Italy. lorenzo.drago@unimi.it
Nicola
L
L
De Vecchi
E
E
D000081:Acetamides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics*; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics*; D000069349:Linezolid; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000187:drug effects; D023303:Oxazolidinones / Q000494:pharmacology; D012641:Selection, Genetic; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*; D017334:Teicoplanin / Q000494:pharmacology; D014640:Vancomycin / Q000494:pharmacology; D014769:Virginiamycin / Q000031:analogs & derivatives / Q000494:pharmacology
D000081:Acetamides; D000900:Anti-Bacterial Agents; D023303:Oxazolidinones; D014769:Virginiamycin; C113825:quinupristin; D017334:Teicoplanin; D014640:Vancomycin; D000069349:Linezolid; C113826:dalfopristin