A 7-year surveillance for ESBL-producing Escherichia coli and Klebsiella pneumoniae at a university hospital in Taiwan: The increase of CTX-M-15 in the ICU

Abstract

To monitor the changing trend of extended-spectrum -lactamase (ESBL)-producing bacteria, a 7-year continuous study was launched in 2001 at the largest tertiary hospital in Taiwan. A significant increase over the study period was evident for ESBL-producing isolates of Escherichia coli (48-100%) and Klebsiella pneumoniae (150-234%). Molecular investigation conducted in three separate periods revealed the prevalent ESBL types and their genetic relatedness. CTX-M-producing isolates (738%) were more prevalent than SHV-type ESBLs (370%), the most frequent being CTX-M-14 (343%), CTX-M-3 (259%), and SHV-12 (257%). However, a marked increase of CTX-M-15-producing isolates from 21% in 2002 to 296% in 2007 was also noted. The increase of ESBL-producing isolates in both species may be mainly due to the horizontal transmission of resistance plasmids, while clonal expansion of some epidemic strains further added to the dispersion of ESBL-producing K. pneumoniae. © 2009 Cambridge University Press.