title: Comparative in vitro activity profile of oritavancin against recent gram-positive clinical isolates.
abstract: Oritavancin activity was tested against 15,764 gram-positive isolates collected from 246 hospital centers in 25 countries between 2005 and 2008. Organisms were Staphylococcus aureus (n = 9,075), coagulase-negative staphylococci (n = 1,664), Enterococcus faecalis (n = 1,738), Enterococcus faecium (n = 819), Streptococcus pyogenes (n = 959), Streptococcus agalactiae (n = 415), group C, G, and F streptococci (n = 84), and Streptococcus pneumoniae (n = 1,010). Among the evaluated staphylococci, 56.7% were resistant to oxacillin. The vancomycin resistance rate among enterococci was 21.2%. Penicillin-resistant and -intermediate rates were 14.7% and 21.4%, respectively, among S. pneumoniae isolates. Among nonpneumococcal streptococci, 18.5% were nonsusceptible to erythromycin. Oritavancin showed substantial in vitro activity against all organisms tested, regardless of resistance profile. The maximum oritavancin MIC against all staphylococci tested (n = 10,739) was 4 microg/ml; the MIC(90) against S. aureus was 0.12 microg/ml. Against E. faecalis and E. faecium, oritavancin MIC(90)s were 0.06 and 0.12, respectively. Oritavancin was active against glycopeptide-resistant enterococci, including VanA strains (n = 486), with MIC(90)s of 0.25 and 1 microg/ml against VanA E. faecium and E. faecalis, respectively. Oritavancin showed potent activity against streptococci (n = 2,468); MIC(90)s for the different streptococcal species were between 0.008 and 1 microg/ml. These data are consistent with previous studies with respect to resistance rates of gram-positive isolates and demonstrate the spectrum and in vitro activity of oritavancin against a wide variety of contemporary gram-positive pathogens, regardless of resistance to currently used drugs. The data provide a foundation for interpreting oritavancin activity and potential changes in susceptibility over time once oritavancin enters into clinical use.
authors.affiliation: The Medicines Company, 7170 Frederick Banting Street, Second Floor, Saint Laurent, Québec, Canada H4S 2A1. francis.arhin@themedco.com
authors.forename: Francis F
authors.initials: FF
authors.lastname: Arhin
authors.forename: Deborah C
authors.initials: DC
authors.lastname: Draghi
authors.forename: Chris M
authors.initials: CM
authors.lastname: Pillar
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Parr
authors.forename: Gregory
authors.initials: G
authors.lastname: Moeck
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Sahm
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D016984:Enterococcus faecium / Q000187:drug effects; D006020:Glycopeptides / Q000494:pharmacology*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006801:Humans; D000077427:Lipoglycopeptides; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000187:drug effects; D013291:Streptococcus / Q000187:drug effects; D014640:Vancomycin / Q000031:analogs & derivatives
chemical_list: D000900:Anti-Bacterial Agents; D006020:Glycopeptides; D000077427:Lipoglycopeptides; C100708:oritavancin; D014640:Vancomycin