Emergence of Enterobacteriaceae isolates producing CTX-M extended-spectrum beta-lactamase in Austria

Among 149 extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae isolates collected from patients in southeast Austria from 1998 to 2004, 38 Escherichia coli isolates and 11 Klebsiella spp. were CTX-M producers. The proportion of CTX-M-producers among all ESBL producers rose from 0% in 1998 to 58% in 2004. In general, CTX-M-producers had heterogeneous pulsed-field gel electrophoresis patterns, but one E. coli isolate was identical to a United Kingdom epidemic CTX-M-15-producing strain, although no epidemiological link with the United Kingdom was apparent.