Occurrence of Extended-Spectrum and AmpC-Type β-Lactamase Genes in Escherichia coli Isolated from Water Environments in Northern Thailand.

Sixty-eight cefotaxime-resistant Escherichia coli isolates were recovered from different water environments in Northern Thailand. Isolates were mostly resistant to ceftazidime and aztreonam (>90%). The most common extended-spectrum β-lactamase-encoding gene was bla (75%) followed by bla (13.2%). The co-existence of bla and AmpC-type β-lactamase genes was detected in 4 isolates (5.9%). Two E. coli isolates carrying bla from canal and river water samples belonged to the phylogenetic group B2-ST131, which is known to be pathogenic. This is the first study on bla and bla-carrying E. coli and the emergence of ST131 from water environments in Thailand.