In Vitro Activities of Daptomycin, Linezolid, and Quinupristin-Dalfopristin against a Challenge Panel of Staphylococci and Enterococci, Including Vancomycin-Intermediate Staphylococcus aureus and Vancomycin-Resistant Enterococcus faecium

• Published in: Microbial drug resistance (Larchmont, N.Y.) Vol. 9; no. 4; pp. 389 - 393
• Main Authors: Jevitt, Laura A., Smith, Amanda J., Williams, Portia P., Raney, Patti M., McGowan, John E., Tenover, Fred C.
• Format: Journal Article
• Language: English
• Published: United States Mary Ann Liebert, Inc 01.12.2003
• Subjects: Acetamides - pharmacology; Anti-Bacterial Agents - pharmacology; Anti-Infective Agents - pharmacology; Antibiotic resistance; Antimicrobial agents; Daptomycin - pharmacology; Disease; Drug Therapy, Combination - pharmacology; Enterococcus faecium; Enterococcus faecium - drug effects; Genes, Bacterial - genetics; Linezolid; Methicillin Resistance; Microbial Sensitivity Tests; Oxazolidinones - pharmacology; Staphylococcus aureus; Staphylococcus aureus - drug effects; Staphylococcus aureus - genetics; Vancomycin Resistance - genetics; Virginiamycin - pharmacology
• ISSN: 1076-6294; 1931-8448
• DOI: 10.1089/107662903322762833

We assessed the in vitro activities of daptomycin, linezolid, and quinupristin-dalfopristin (QD) against a contemporary challenge panel of 88 staphylococcal and 90 enterococcal isolates. The staphylococci selected included vancomycin-intermediate Staphylococcus aureus (VISA), methicillin-resistant S. aureus , and coagulasenegative staphylococci. Enterococcal isolates included vancomycin-resistant Enterococcus faecium (VREF) containing either van A, van B1, or van D. The MICs of daptomycin, linezolid, and QD were determined using commercial broth microdilution panels. All three VISA isolates were susceptible to daptomycin, linezolid, and QD. QD was the most active agent against staphylococcal isolates (MIC 50 ≤ 0.5μg/ml and MIC 90 = 1μg/ml), including those with decreased susceptibility to vancomycin. QD was also the most active agent against VREF (MIC 90 ≤ 0.5μg/ml). No differences were seen for susceptibility of van A, van B1, and van D VREF strains for daptomycin, linezolid, or QD. Daptomycin was the most effective against E. faecalis . On the basis of manufacturer-suggested interpretive criteria, 92% of isolates were susceptible (MIC 90 = 4μg/ml). All isolates tested were susceptible to at least one antimicrobial agent for which interpretive criteria have been defined. Population analysis of three S. aureus isolates for which the daptomycin MICs were 8μg/ml showed a pattern of homogeneous resistance.