In vitro activity of tigecycline against clinical isolates of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, Serratia marcescens and Enterobacter cloacae

Background and Purpose: Strains of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae have spread widely in Taiwan hospitals. In this study, we evaluated the in vitro antimicrobial activity of tigecycline against ESBL-producing Enterobacteriaceae, including Klebsiella pneumoniae, Serratia marcescens and Enterobacter cloacae. Methods: 104 confirmed ESBL-producing bacteria were isolated from 4 hospitals in mid- and southern Taiwan between 2000 and 2006. The in vitro activity of tigecycline against these ESBL producers was tested by use of Etest strips. Results: The minimal tigecycline concentration at which 50% of isolates were inhibited and minimal concentration at which 90% of isolates were inhibited for ESBL-producing isolates ranged from 0.38 to 0.75 μg/mL and 0.5 to 1.5 μg/mL, respectively. Conclusions: Tigecycline, a new semisynthetic glycylcycline, may be considered an alternative drug of choice for patients infected with ESBL-producing bacteria.