山东省兰陵县羊粪中产志贺毒素2k新亚型大肠埃希菌的检出及其分子特征分析

Identification and characterization of Escherichia coli strains producing a novel Shiga toxin 2k subtype in goat feces in Lanling county,Shandong province

目的了解山东省兰陵县羊携带志贺毒素基因stx2k新亚型大肠埃希菌的情况及其分子特征。方法2019年11月采集山东省兰陵县不同养殖户的羊粪便512份,经EC肉汤增菌后PCR检测stx基因,阳性样品分别接种科玛嘉(CHROMagar^TM)ECC及科玛嘉(CHROMagar^TM)STEC培养基,对stx基因阳性菌株进行全基因组测序。根据基因组数据分析菌株stx基因亚型、血清型、多位点序列分型(MLST)情况及毒力基因携带情况。结果从512份羊粪中共分离86株产志贺毒素大肠埃希菌,包括5种不同的stx亚型,其中stx2k亚型菌株37株;86株菌分为20种O∶H血清型及18种不同ST型。结论山东省兰陵县羊携带的产志贺毒素大肠埃希菌在志贺毒素亚型、血清型及毒力基因等分子特征方面存在多样性,且检出了产志贺毒素2k新亚型的大肠埃希菌。

Objective To investigate the prevalence and molecular characteristics of Escherichia coli(E.coli)producing a novel Shiga toxin 2k subtype in goat in Lanling county,Shandong province.Methods In November 2019,512 goat fecal samples were collected from different households in Lanling county,Shandong province.After enriched with EC broth,stx-positive samples were detected by PCR and inoculated in CHROMagar™ECC agar and CHROMagar™STEC agar.The whole genomes of stx-positive strains were sequenced.Based on the genomic senquences,the stx subtype,serotype,multi-locus sequence type and virulence genes of each strain were analyzed.Results Eighty-six strains of Shiga toxin-producing E.coli(STEC)were isolated from 512 goat fecal samples.Five stx subtypes were identified and 37 strains were positive for stx2k.The 86 STEC strains belonged to 20 O∶H serotypes and 18 different sequence types(STs).Conclusions STEC strains circulating in goats in Lanling county,Shandong province were heterogeneous in stx subtypes,serotypes and virulence gene profiles,and a certain proportion of strains producing a novel Shiga toxin 2k subtype were detected.