Dalbavancin activity against selected populations of antimicrobial-resistant Gram-positive pathogens

Dalbavancin, a dimethylaminepropyl amide derivative of the lipoglycopeptide A40926, was tested against 375 antimicrobial-resistant Gram-positive pathogens collected worldwide during 2001-2003. The isolates were tested by reference and Clinical Laboratory Standards Institute broth microdilution susceptibility methods, and dalbavancin was compared with over 20 other antimicrobials. Vancomycin resistance determinants among enterococci were identified using PCR primer sets for vanA and vanB. Dalbavancin was generally more potent than vancomycin or teicoplanin. Dalbavancin was highly active against penicillin- and ceftriaxone-resistant Streptococcus pneumoniae strains (MIC90, ≤ 0.016 μg/mL). Dalbavancin was also very active against teicoplanin-nonsusceptible coagulase-negative staphylococci (CoNS; MIC range, 0.03-0.25 μg/mL), but dalbavancin MIC results were slightly elevated compared with wild type strains. Dalbavancin inhibited vanB enterococci (MIC range, 0.03-0.12 μg/mL) and was active against other resistant, non-vanA enterococcal species. However, vanA enterococcal strains were not as susceptible to dalbavancin (MIC50, 16 μg/mL). In summary, dalbavancin was very active against a wide spectrum of resistant Gram-positive isolates and demonstrated greater potency than vancomycin or teicoplanin.