Dalbavancin Comparative Activity Tested Against Gram-positive Species in German Medical Centers: Results from the DECIDE Program

Abstract

Background: Dalbavancin, a long-acting glycolipopeptide, was tested against clinical isolates from four hospitals in Germany in the last quarter of 2007. Methods: Investigators used standardized and referencequality agar diffusion methods including Etest (ET; AB BIODISK) and CLSI disk diffusion (DD) tests with concurrent QC and repeated testing of strains showing unusual resistance patterns such as linezolid resistance and vancomycin or dalbavancinnon-susceptibility. 150 strains were tested (100 S. aureus [SA], 20 coagulase-negative staphylococci [CoNS], 30 s-haemolytic streptococci [BHS] with most being group A or S. pyogenes) against dalbavancin and vancomycin by ET; and linezolid, cefoxitin (determination of methicillin resistance), levofloxacin, gentamicin, tetracycline, erythromycin, clindamycin (plus D-test), penicillin and ceftriaxone by DD. All German sites having acceptable QC results were tabulated. Dalbavancin susceptibility was defined at ≤0.25 mg/L. Results: Dalbavancin exhibited excellent activity against SA (MIC 50/90 , 0.047/0.125 mg/L), CoNS (MIC 50/90 , 0.047/0.19 mg/L) and BHS (MIC 50/90 , ≤0.016/0.032 mg/L). This activity was 16- to 32-fold greater than vancomycin. MRSA rates were low (8%) but varied modestly from 4 to 12% among hospitals. S rates were: linezolid (100%), levofloxacin (55-83%), erythromycin (5080%), and clindamycin (65-84%). D-test positive rates were 3386% for the SA, CoNS and BHS; overall clindamycin-resistant at 16% for SA, but nil for BHS. SA was also very susceptible to gentamicin (95%) and tetracycline (93%). Methicillin susceptibility or resistance did not influence dalbavancin potency versus SA or CoNS. Highest recorded dalbavancin MIC was 0.38 mg/L, two confirmed staphylococci from Frankfurt. Some German centers read Etest results higher (0.5-1.0 log 2 ) than other laboratories in Europe.