In vitro activity of telithromycin, quinupristin/dalfopristin, linezolid and comparator antimicrobial agents against Staphylococcus aureus clinical isolates.
We have studied the prevalence of the different macrolide, lincosamide, streptograminB (MLS(B)) phenotypes among clinical Staphylococcus aureus isolates erythromycin- and/or oxacillin-resistant; and also the activity of other antimicrobial agents including telithromycin, quinupristin/dalfopristin, linezolid, aminoglycosides, chloramphenicol and vancomycin. We found that 64.86% of S. aureus were oxacillin-resistant. While the most prevalent MLS(B) phenotype among methicillin-resistant S. aureus (MRSA) was constitutive MLS(B) (cMLS) (83%), among methicillin-susceptible S. aureus (MSSA) it was inducible MLS(B) (iMLS(B)) (90%). Kanamycin resistance was more frequent than resistance to other aminoglycosides, being 100% for MRSA. Telithromycin was only active against iMLS(B), MS and erythromycin-susceptible isolates, although resistance rates were found among iMLS(B) MSSA (2.78%). Quinupristin/dalfopristin showed greater activity, with resistance rates of 2.5% for MRSA and 1.53% for MSSA. Both vancomycin and linezolid were fully active against all the isolates tested, with the highest MIC value being 2 microg/ml and 4 microg/ml, respectively. Among MRSA strains, 81.67% displayed resistance to five or more antimicrobials. This multiresistance was more frequently found among cMLS(B) strains (96.38% MRSA resistant to 6-9 agents).
Department of Microbiology, Faculty of Medicine, University of Zaragoza, Clinical University Hospital Lozano Blesa, c/ Domingo Miral s/n, 50009 Zaragoza, Spain.
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Millán
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Cerdá
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Rubio
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Goñi
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Canales
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Gómez-Lus
D000081:Acetamides / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D048628:Ketolides; D000069349:Linezolid; D018942:Macrolides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D023303:Oxazolidinones / Q000494:pharmacology*; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D013030:Spain; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D014769:Virginiamycin / Q000031:analogs & derivatives* / Q000494:pharmacology*
D000081:Acetamides; D048628:Ketolides; D018942:Macrolides; D023303:Oxazolidinones; D014769:Virginiamycin; C113825:quinupristin; D000069349:Linezolid; C106791:telithromycin; C113826:dalfopristin