Objective: Dalbavancin is the novel semi-synthetic lipoglycopeptide antibacterial possessing in vitro activity against a variety of gram-positive pathogens. Due to its prolonged half-life, dalbavancin can be used in clinical trials, once-weekly dosing strategies. The aim of the study was to determine the activity of dalbavancin against staphylococcal isolates by microdilution method.
Material and method: In the study, totaly 453 staphylococcal isolates isolated from some patients who attended to Istanbul Faculty of Medicine's Hospital between 2005 and 2007 were tested. The distribution of species was oxacillin-resistant Staphylococcus aureus (ORSA): 237, oxacillin-susceptible Staphylococcus aureus (OSSA): 144, and oxacillin-resistant coagulase-negative staphylococci (OR-CoNS): 72. Antimicrobial susceptibility testing was performed using broth microdilution method by Clinical and Laboratory Standards Institute (CLSI). Mueller-Hinton broth with 0.002% polysorbate-80 was used (CLSI M7-A7). Dalbavancin (Pfizer Inc. Groton, CT) was dissolved in DMSO then diluted in distilled water. The range used was 0.008-4 µg/ml. Quality control (QC) of test procedures were monitored via testing of the reference strains S. aureus ATCC 29213 and E. faecalis ATCC 29212 in each run (CLSI M100-S15).
Results: A susceptibility breakpoint for dalbavancin has not been established by CLSI. Against ORSA, OSSA and OR-CoNS, dalbavancin MIC50 and MIC90 values were ≤ 0.008 and 0.25µg/ml; 0.016 and 0.125 µg/ml; 0.016 and 0.5 µg/ml, respectively. The overall distribution of dalbavancin MIC values ranged ≤ 0.008-2 µg/ml.