猪源致病性大肠杆菌的血清型、毒力基因及抗菌药耐药性的调查

【目的】探讨猪大肠杆菌病分离的E.coli的优势血清型与毒力基因和耐药性的相关性。【方法】采用玻片凝集法测定了猪大肠杆菌病有关的血清型分布,PCR方法调查7种毒力相关基因,用微量稀释法测定了所有菌株对18种抗菌药的敏感性。【结果】超过一半的菌株含有astA,Stx2e和eaeA基因,且毒力基因组合Stx2e+astA和Stx2e+eaeA较为流行。定型菌株53株,分别属于15个不同的血清型,其中O8和O64为主要流行的血清型。O8型菌株中,所有均携带astA基因,多数耐四环素、环丙沙星、恩诺沙星、氯霉素和磺胺甲噁唑,但对安普霉素,阿米卡星和多黏菌素E敏感;而O64型菌株中,多数携带astA和Stx2e基因,所有对环丙沙星、恩诺沙星、氯霉素和磺胺甲噁唑耐药,但对多黏菌素E和卡那霉素敏感。【结论】O8和O64为主要流行的血清型,两种血清型菌株拥有相似的毒力基因谱和耐药表型,但有不同的敏感表型。

Prevalence of Serotypes and Virulence Genes and Antimicrobial Susceptibility of Pathogenic Escherichia coil Isolates from Swine

【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.