Nationwide Surveillance in Taiwan of the in-Vitro Activity of Tigecycline against Clinical Isolates of Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae

Abstract

Tigecycline In-vitro Surveillance in Taiwan (TIST), initiated in 2006, is a nationwide surveillance programme designed to monitor longitudinally the in-vitro activity of tigecycline against commonly encountered resistant bacteria. This study compared the in-vitro activity of tigecycline against clinical isolates of resistant Gram-negative bacteria determined by the broth microdilution and Etest methods. A total of 622 isolates were collected from patients treated at 20 teaching hospitals. Tigecycline had excellent in-vitro activity against extended-spectrum beta - lactamase (ESBL)-producing Escherichia coli (N = 275) with MIC90 0.5 mu g/mL and a 99.6% susceptibility rate, and also against ESBL-producing Klebsiella pneumoniae ( N = 324) with MIC90 2 mu g/mL and a 98.5% susceptibility rate. For ESBL- producing Proteus mirabilis (N = 15) the MIC90 was 4 mu g/mL with a 73.3% susceptibility rate. For ESBL-producing Klebsiella oxytoca (N = 8) the MIC50 and MIC90 were 0.5 and 1 mu g/mL, respectively, with a 100% susceptibility rate. Limited agreement (< 80%) was found between the broth microdilution and the Etest methods when determining the in- vitro activity of tigecycline against ESBL-producing K . pneumoniae and K. oxytoca. (C) 2008 Elsevier B. V. and the International Society of Chemotherapy.