Analysis of 5-year trends in daptomycin activity tested against Staphylococcus aureus and enterococci from European and US hospitals (2009–2013)

• Daptomycin demonstrated sustained activity against MRSA and VRE from Europe and the USA.
• More than 99.9% of contemporary clinical strains were susceptible to daptomycin.
• Daptomycin was more potent compared with vancomycin and linezolid against MRSA.
• Daptomycin activity was not influenced by oxacillin resistance among S. aureus.
• Daptomycin activity was not influenced by vancomycin resistance among enterococci.

This study evaluated daptomycin activity trends among meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) over a 5-year period (2009–2013). Consecutive, unique patient isolates of clinical significance were collected in 67 European (EU) (17 nations) and 145 US medical centres and were susceptibility tested in a central reference laboratory against daptomycin and various comparators by CLSI broth microdilution methods. MIC results were interpreted according to EUCAST and CLSI breakpoint criteria (2014). A total of (EU/USA) 14 245/22 967 S. aureus (26.3/49.8% MRSA), 3043/2848 Enterococcus faecalis (1.6/3.5% vancomycin-resistant) and 1827/1537 Enterococcus faecium (29.5/77.7% vancomycin-resistant) were evaluated. Isolates were mainly from complicated skin and skin-structure infections (40%) and bacteraemia (32%). The highest MRSA rates were found in Portugal (66.3%), Russia (52.2%) and the USA (49.8%), whereas the highest rates of vancomycin-resistant E. faecium (VREFM) were observed in the USA (77.7%), Poland (63.1%) and Ireland (54.5%). VREFM and vancomycin-resistant E. faecalis (VREF) were observed in 15 and 8 EU nations, respectively. Daptomycin susceptibility rates were (EU/USA) 99.94/99.97%, 100.0/99.7% and 100.0/99.96% for S. aureus, E. faecium and E. faecalis, respectively. Daptomycin was very active against MRSA (MIC50/90, 0.25/0.5 mg/L in Europe and USA), VREF (MIC50/90 of 0.5/1 mg/L and 1/2 mg/L in Europe and USA, respectively) and VREFM (MIC50/90, 2/2 mg/L in Europe and USA). Among MRSA, only 6/6 (0.19/0.05%) daptomycin-non-susceptible isolates were observed in Europe (six cities in four countries)/USA (six states), with no increasing trend over the study period. Only two daptomycin-non-susceptible VRE were identified, both E. faecium from the USA.