Outcomes with daptomycin in the treatment of Staphylococcus aureus infections with a range of vancomycin MICs

Abstract

ObjectivesRecent recommendations by the Infectious Diseases Society of America for the treatment of Staphylococcus aureus suggest the use of alternative agents when vancomycin MIC values are ≥2 mg/L. This study examines the outcome of patients treated with daptomycin for S. aureus infections with documented vancomycin MICs.Patients and methodsAll patients with skin, bacteraemia and endocarditis infections due to S. aureus with vancomycin MIC values in CORE 2005–08, a retrospective, multicentre, observational registry, were studied. The outcome (cure, improved, failure or non-evaluable) was the investigator assessment at the end of daptomycin therapy. Success was defined as cure or improved.ResultsFive hundred and forty-seven clinically evaluable patients were identified with discrete vancomycin MIC values [MIC <2 mg/L: 451 (82%); MIC ≥2 mg/L: 96 (18%)]. The vancomycin MIC groups were well matched for patient characteristics, types of infections, first-line daptomycin use (19%) and prior vancomycin use (58%). Clinical success was reported in 94% of patients. No differences were detected in the daptomycin success rate by the vancomycin MIC group overall or by the infection type. A multivariate logistic regression also failed to identify vancomycin MIC as a predictor of daptomycin failure. Adverse event (AE) rates were not different when analysed by MIC group; both groups had ∼17% of patients with one AE.ConclusionsIn this diverse population, daptomycin was associated with similar outcomes for patients, regardless of whether the vancomycin MIC was categorized as <2 or ≥2 mg/L. Further studies are warranted.

Influence of early daptomycin therapy on treatment outcome of meticillin-resistant Staphylococcus aureus bacteraemia with high vancomycin minimum inhibitory concentrations

“…Clinical outcomes and mortality are shown in Table 1 The optimum alternative treatment regimen for MRSA bacteraemia with higher vancomycin MICs is still unclear. As reported previously, daptomycin is non-inferior to vancomycin in patients with bacteraemia, infective endocarditis and complicated skin and skin-structure infections caused by MRSA [4,5]. However, these studies included a diverse disease spectrum with or without bacteraemia, a broad range of vancomycin MICs and non-strict definitions for daptomycin therapy.…”

High vancomycin minimum inhibitory concentration and clinical outcomes in adults with methicillin-resistant Staphylococcus aureus infections: a meta-analysis

“…Some studies have shown no significant association between higher MICs and poor outcomes, 7,8 but others have suggested an association with increased treatment failures and higher mortality. 9-13 Unfortunately, there are many differences in variables between individual studies (different patient populations, laboratory methods, outcome measures, etc.)…”

Daptomycin Improves Outcomes Regardless of Vancomycin MIC in a Propensity-Matched Analysis of Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

“…Most recently, Weston et al reported higher clinical failure rates among vancomycin-treated patients than daptomycin-treated patients (51.0% versus 34.0%; P ϭ 0.048) and noted that the outcomes did not change in those treated with daptomycin, regardless of renal function (16). Currently, there are few studies that have directly addressed the impact of elevated vancomycin MICs on patient outcomes when patients are treated with daptomycin for MRSA BSIs and the current literature has failed to demonstrate the same association between outcomes and elevated MIC as with vancomycin-treated patients, making daptomycin an ideal treatment alternative (17).…”