title: In vitro activity of daptomycin and comparator agents against Staphylococcus aureus isolates from intravenous drug users with right endocarditis.
abstract: There is an increasing need for alternative agents in endocarditis, especially with the increasing incidence of vancomycin-intermediate Staphylococcus aureus (VISA). We evaluated the in vitro activity of daptomycin and several comparator agents against 33 non-duplicate clinical Staphylococcus aureus isolates from intravenous drug users with right endocarditis. Wider microdilution panels were used for all the comparator agents and daptomycin. Daptomycin was also tested using E-test strips. E-test strips were used to confirm the vancomycin MICs. Methicillin-resistant Staphylococcus aureus (MRSA isolates with vancomycin MICs ≥ 2 g/mL were screened using the E-test GRD. In all, 30 isolates were methicillin-susceptible (MSSA) and 3 MRSA. The three MRSA isolates exhibited a false vancomycin MIC >2 g/mL determined by Wider microdilution panels. They were screened using the E-test GRD and they were GRD negative. Their final MIC was 2 g/mL. Three MSSA and three MRSA isolates had a vancomycin MIC of 2 g/mL. Four MSSA isolates had a vancomycin MIC of 1.5 g/mL, daptomycin MIC90 0.25 g/mL, linezolid MIC90 2 g/mL. As regards daptomycin, wider microdilution panels and E-test strips yielded the same results. Our findings suggest that daptomycin and linezolid are a viable alternative for treating right endocarditis and bacteraemia caused by MSSA, MRSA and hVISA.
authors.affiliation: Department of Microbiology, Hospital of La Línea, Cádiz, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Sanchez-Porto
authors.forename: Manuel
authors.initials: M
authors.lastname: Casanova-Roman
authors.forename: Javier
authors.initials: J
authors.lastname: Casas-Ciria
authors.forename: Maria Jose
authors.initials: MJ
authors.lastname: Santaella
authors.forename: Immaculada
authors.initials: I
authors.lastname: Sanchez-Morenilla
authors.forename: Jose Maria
authors.initials: JM
authors.lastname: Eiros-Bouza
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016470:Bacteremia / Q000150:complications / Q000382:microbiology; D002462:Cell Membrane / Q000187:drug effects; D015169:Colony Count, Microbial; D017576:Daptomycin / Q000494:pharmacology*; D004353:Drug Evaluation, Preclinical; D024901:Drug Resistance, Multiple, Bacterial; D004697:Endocarditis, Bacterial / Q000209:etiology / Q000382:microbiology*; D006801:Humans; D066298:In Vitro Techniques; D000069349:Linezolid; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D023303:Oxazolidinones / Q000494:pharmacology; D011934:Reagent Strips; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D015819:Substance Abuse, Intravenous / Q000150:complications*; D020713:Vancomycin Resistance
chemical_list: D000081:Acetamides; D000900:Anti-Bacterial Agents; D023303:Oxazolidinones; D011934:Reagent Strips; D000069349:Linezolid; D017576:Daptomycin