Daptomycin activity against nine strains of Enterococcus faecalis with a high inoculum and exponential or stationary growth phase bacteria, statistical analysis.

<p>Nine strains of <i>Enterococcus faecalis</i> were used, including: 6 clinical strains obtained from patients presenting endocarditis (OB, FAM, ME, LH, FG, ZM); 1 clinical strain obtained from enterococcus bacteriemia without endocarditis (CR) and 2 reference strains (JH2-2, ATCC 11700). In conditions of high inoculum and with exponential growth phase bacteria daptomycin activity at 120 µg/ml was significantly higher than daptomycin at 60 µg/ml (<i>p</i><0,0001) and than the combination amoxicillin-gentamicin (<i>p</i><0,0001) (A). In conditions of high inoculum and with stationary growth phase bacteria daptomycin activity at 120 µg/ml and pH 7 was significantly higher than daptomycin at 120 µg/ml and pH 5 (<i>p</i><0,0001), than daptomycin at 60 µg/ml and pH 7 (<i>p</i><0,0001), but not significantly higher than daptomycin at 120 µg/ml and pH 6 (<i>p</i> = 0,0537). Median changes in CFU/ml at 24 h were compared by Mann-Whitney <i>U</i>-test. A <i>p</i> value of ≤0.05 was considered significant. All statistical analyses were performed using GraphPad Prism software 6.0 (GraphPad, San Diego, CA, USA).