Abstract:

【Objective】 The aim of the study was to investigate the prevalence of serotypes, virulence genes and resistance phenotypes of Escherichia coli isolates from swine. 【Method】 O serogroups were identified by agglutination with specific antisera. Resistance phenotypes were tested by the broth microdilution. All strains were screened for virulence genes by PCR. 【Result】 The finding showed that more than 50% of E. coli isolates possessed astA, Stx2e and eaeA genes, while the combinations of Stx2e+astA and Stx2e+eaeA were more prevalent. Fifteen O serogroups were identified for 53 E. coli isolates, of which O8 and O64 were dominant serogroups. All strains of O8 serogroup carried astA gene, most of the O8 strains were resistant to tetracycline, ciprofloxacin, enrofloxacin and chloramphenicol, but were susceptible to apramycin , amikacin and polymyxin E. While most of the O64 strains possessed astA and Stx2e, and also were resistant to ciprofloxacin, enrofloxacin, chloramphenicol and sulfamethoxazol, but were susceptible to kanamycin and polymyxin E. 【Conclusion】 It is concluded that O8 and O64 are dominant serogroups associate with the disease of swine, both serogroups harbor similar virulence genes and resistant phenotypes, but present different susceptibility phenotypes.

Key words: serogroups, virulence genes, resistance, Escherichia coli