Evaluation of in vitro activity of quinupristin/dalfopristin and comparator antimicrobial agents against worldwide clinical trial and other laboratory isolates.
This report summarizes the activities of quinupristin/dalfopristin (Q/D) and appropriate comparator antibiotics, including ciprofloxacin, erythromycin, gentamicin, rifampin, teicoplanin, and vancomycin, against selected gram-positive pathogens, including Enterococcus faecium, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus agalactiae, and Streptococcus pyogenes. The study pathogens were obtained from 2 sources: (1) clinical isolates taken from patients participating in Q/D worldwide Phase III comparative and noncomparative (emergency-use program) clinical trials; and (2) other isolates collected from the laboratories of 45 geographically distinct medical centers around the world. Q/D was highly active, with minimum inhibitory concentrations (MICs) < or = 1.0 microg/mL against most isolates, including those known to be resistant to methicillin, vancomycin, or erythromycin. Q/D was active (MICs < or = 1 microg/mL) against 95% of the vancomycin-resistant E. faecium strains, for example, whereas ciprofloxacin was active against 6%. Q/D was equally active against methicillin-susceptible or -resistant S. aureus strains (MIC90=1 microg/mL), as was vancomycin (MIC90=2 microg/mL), whereas ciprofloxacin was much less active against methicillin-resistant strains than against methicillin-susceptible strains (MIC90=32 vs 1 microg/mL). Given its spectrum of activity, Q/D may provide a viable option for the treatment of severe respiratory and skin and skin-structure infections caused by gram-positive bacteria, especially when strains with known or suspected resistance to other commonly used antibiotics are present.
Rhône-Poulenc Rorer Pharmaceuticals, Collegeville, Pennsylvania 19426, USA.
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D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D017326:Clinical Trials, Phase III as Topic; D018432:Drug Resistance, Multiple; D016984:Enterococcus faecium / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006801:Humans; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D013212:Staphylococcus epidermidis / Q000187:drug effects; D014640:Vancomycin / Q000494:pharmacology; D014769:Virginiamycin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D014769:Virginiamycin; C062940:quinupristin-dalfopristin; D002939:Ciprofloxacin; D014640:Vancomycin