Influence of the minimum inhibitory concentration of daptomycin on the outcomes of Staphylococcus aureus bacteraemia

Recent studies have shown that methicillin-resistantStaphylococcus aureus (MRSA) bacteraemia with vancomycin minimum inhibitory concentration (MIC) >1 μg/mL is associated with a higher rate of treatment failure and a higher mortality rate. Daptomycin is an alternative to vancomycin but has not been as well studied. The aim of this literature review was to evaluate the effect of daptomycin MIC on the outcomes of S. aureus bacteraemia.

We conducted a literature search for the period January 2010 to January 2019 using the MEDLINE and Embase databases.

Four studies were included in the review. The outcomes were clinical cure and 30- or 60-day mortality. In two retrospective studies, 60-70% ofS. aureus isolates had a low daptomycin MIC (≤0.5 μg/mL) and patients with MRSA bacteraemia who were treated with daptomycin had a lower mortality rate. In another study, patients with methicillin-susceptible S. aureus bacteraemia with low daptomycin MICs had a lower risk of developing septic thrombophlebitis. One study showed that patients with MRSA bacteraemia had a higher mortality rate if the daptomycin MIC was >0.5 μg/mL.

The included studies in this review suggest a possible association between high daptomycin MIC and unfavourable clinical outcomes ofS. aureus bacteraemia. Further prospective studies are required to evaluate the impact of the daptomycin MIC on the clinical outcomes of S. aureus bacteraemia.