Shift of CTX- M genotypes has determined the increased prevalence of extended-spectrum β-lactamase-producing Escherichia coli in south-western Sweden.

The prevalence of Escherichia coli producing extended-spectrum β-lactamases ( ESBLs) markedly increased during 2004-2008 in south-western Sweden, with a greater increase in urinary isolates in hospitals (0.2-2.5%) than in the community (0.2-1.6%). ESBLs of genotype CTX- M predominated, with a significant (p <0.02) shift from the CTX- M-9 to CTX- M-1 phylogroup occurring among urinary ESBL-producing E. coli isolated early ( n = 41) as compared with late ( n = 221) in the study period. The increase in ESBL-producing E. coli was polyclonal, and only partly attributable to an increase (0-24%) in the number of O25b- ST131 isolates carrying CTX- M-15. The increase was prominent in men and in elderly patients, and warrants continued surveillance. [ABSTRACT FROM AUTHOR]