Longitudinal analysis of the in vitro activity profile of oritavancin and comparator glycopeptides against Gram-positive organisms from Europe: 20052008

Abstract number: P1620

Draghi D., Pillar C., Moeck G., Arhin F., Sahm D.

Objective: Oritavancin (ORI), currently in clinical development for use in the treatment of infections caused by Gram-positive (GP) bacteria, is a potent bactericidal lipoglycopeptide. ORI has previously shown potent activity against GP organisms, including resistant (R) strains. This comparative analysis was undertaken to profile the in vitro activity of ORI in Europe (EU) across multiple years.

Methods: In total 2036, recent (2005–2008) clinical isolates of S. aureus (SA; n = 757), coagulase-negative staphylococci (CoNS; n = 340), Enterococcus spp. (EN; n = 492), S. pyogenes (GAS; n = 235), and S. agalactiae (GBS; n = 212) from 49 hospital sites in EU (15 countries) were centrally tested by broth microdilution (CLSI; M7-A7) against ORI, teicoplanin (TEI), and vancomycin (VAN). ORI assays included 0.002% polysorbate-80 throughout.

Results: ORI MIC90 s ranged from 0.12–0.25 mg/L for SA across all years studied; MIC90 s for VAN (1 mg/L) and TEI (0.5–2 mg/L) were 4–16 fold higher, comparatively. For CoNS, ORI MIC90 s ranged from 0.12–0.25 mg/L across all years studied; MIC90 s for VAN (2 mg/L) and TEI (2 to 8 mg/L) were 16–64 fold higher, comparatively. ORI modal MICs, MIC50 s, and MIC90 s by year were generally equivalent (leqslant R: less-than-or-eq, slant1 doubling dilution) against oxacillin (OX)-susceptible (S) and -R staphylococci (STA). The ORI MIC90 for VAN-S EN was 0.06 mg/L from 2005 to 2008. For the VAN-S population MIC90 s for TEI (0.25–0.5 mg/L) and VAN (2 mg/L) were consistently higher compared with ORI each year. For VAN-non S EN (2005 only), ORI MIC90 was 0.5 mg/L compared to 256 mg/L and >256 mg/L for TEI and VAN, respectively. ORI MIC90 s ranged from 0.12 to 0.25 mg/L against GAS and 0.25–0.5 for GBS, including both erythromycin-S and -R isolates, similar to the MIC90 s of VAN (GAS: 0.25 mg/L; GBS: 0.5 mg/L) and slightly higher than those of TEI (GAS: leqslant R: less-than-or-eq, slant0.03 mg/L; GBS: 0.12 mg/L).

Conclusions: No trend towards decreased susceptibility or elevated MICs was apparent for ORI or comparator agents over time against the evaluated GP cocci. ORI was more potent than comparator glycopeptides against both STA and EN, including resistant isolates, across the evaluated years.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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