| Summary: | <p>Abstract</p> <p>A total of 318 <it>Escherichia coli </it>isolates obtained from different food-producing animals affected with colibacillosis between 2001 and 2006 were subjected to phylogenetic analysis: 72 bovine isolates, 89 poultry isolates and 157 porcine isolates. Overall, the phylogenetic group A was predominant in isolates from cattle (36/72, 50%) and pigs (101/157, 64.3%) whereas groups A (44/89, 49.4%) and D (40/89, 44.9%) were predominant in isolates from poultry. In addition, group B2 was not found among diseased food-producing animals except for a poultry isolate. Thus, the phylogenetic group distribution of <it>E. coli </it>from diseased animals was different by animal species. Among the 318 isolates, cefazolin resistance (minimum inhibitory concentrations: ≥32 μg/ml) was found in six bovine isolates, 29 poultry isolates and three porcine isolates. Of them, 11 isolates (nine from poultry and two from cattle) produced extended spectrum β-lactamase (ESBL). The two bovine isolates produced <it>bla<sub>CTX-M-2</sub></it>, while the nine poultry isolates produced <it>bla<sub>CTX-M-25 </sub></it>(4), <it>bla<sub>SHV-2 </sub></it>(3), <it>bla<sub>CTX-M-15 </sub></it>(1) and <it>bla<sub>CTX-M-2 </sub></it>(1). Thus, our results showed that several types of ESBL were identified and three types of β-lactamase (SHV-2, CTX-M-25 and CTX-M-15) were observed for the first time in <it>E. coli </it>from diseased animals in Japan.</p>
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