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 microg/mL and 0.5 to 1.5 microg/mL, respectively. CONCLUSIONS Tigecycline, a new semisynthetic glycylcycline, may be considered an alternative drug of choice for patients infected with ESBL-producing bacteria.