In Vitro Potency of Tigecycline Against Pathogens from Most Common Body Sites: A Study in Asia/Pacific Rim

Abstract

Objectives: Surveillance studies can identify patterns of resistance and assist in empiric antibiotic choices as resistance can vary by organism and body site isolation. The Tigecycline Evaluation Surveillance Trial (T.E.S.T.) is an ongoing global study that can serve to help recognize resistance by body site. This report evaluates differences in susceptibility of strains from different body sites, collected in Asia/Pacific Rim 2004–2007. Methods: 4057 strains isolated from 8 specimen types were collected and identified from 2004 to 2007 at 23 hospitals in 9 countries in Asia/Pacific Rim. MICs for each strain were determined per CLSI guidelines at each facility using broth microdilution. MIC50/90 values were analyzed to identify any significant differences in antibiograms from different sources. Results: Tigecycline (TIG) MIC50 values for almost all organism/specimen pairings were ±2 dilutions of each other, with no single source giving a higher MIC50 than others. The same was seen for TIG MIC90 values, which were almost always within 1–2 dilutions of the MIC50. Comparator drugs generally showed similar absence of variability in activity vs. isolates from various body sites; however, their MIC90/MIC50 ratios were usually much higher than those of TIG. Even imipenem had such high ratios with Acinetobacter and Enterococus spp. Conclusions: Bacteria isolated from more than 10 different body sites had generally similar antibiograms, with no single source showing significantly different sensitivity patterns. TIG demonstrated a broad spectrum of activity and consistently low MIC90/50 ratios, including strains resistant to other drugs (MRSA, ESBL-producers, and imipenem-resistant Acinetobacter).