In vitro evaluation of tigecycline against drug-resistant Enterococci and S. aureus in the United States

Abstract number: P1729

Johnson J., Hoban D., Johnson B., Bouchillon S., Stevens T., Dowzicky M.

Background: Tigecycline (TIG), a member of a new class of antimicrobials (glycylcyclines), has been shown to have potent activity against many Gram-positive and -negative organisms. The T.E.S.T. Program determined the in vitro activity of TIG against S. aureus and enterococci resistant to 10 commonly prescribed antimicrobials: amoxicillin-clavulanic acid (AUG), piperacillin-tazobactam (PT), levofloxacin (LVX), ceftriaxone (CAX), linezolid (LZD), minocycline (MIN), vancomycin (VAN), ampicillin (AMP), penicillin (P) and imipenem (IMP). Study strains were collected from hospitals globally throughout 2004–2006.

Methods: A total of 7,343 clinical isolates (2,903 enterococci, 4,440 S. aureus) from 193 labs in the United States were identified to the species level at each participating site and confirmed by the central laboratory. Minimum Inhibitory Concentrations (MICs) were determined by the local laboratory using broth microdilution panels. Antimicrobial resistance was interpreted according to CLSI and FDA (TIG) breakpoints.

Results: 840 (29%) enterococci and 1706 (38%) S. aureus (including MR + MS strains) were resistant to two or more drug classes. Among the enterococci, resistance rates were LVX 99%, P 85%, AMP 84%, VAN 76%, MIN 9%, and LZD 0%. Resistant rates for S. aureus were P 100%, AMP 100%, AUG 74%, LVX 99%, PT 63%, CAX 44%, IMP 15%, LZD 0%, MIN 0.2% and VAN 0%. TIG inhibited 100% of all the enterococci and S. aureus resistant to other drugs. Modal TIG MICs ranged between 0.06 and 0.12 mg/ml and were generally the same for most resistant and susceptible strains.

Conclusions: TIG retained potent activity against drug-resistant S. aureus and enterococcal isolates, inhibiting 100% of all resistant strains tested. TIG should prove to be a useful drug for therapy of infections with these resistant Gram-positive pathogens.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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