川西北牦牛源产肠毒素大肠杆菌的分子流行病学调查

为调查川西北地区牦牛源产肠毒素大肠杆菌的流行情况,对采自川西北甘孜州和阿坝州的26份腹泻牦牛粪便样品进行大肠杆菌分离,分别以分离的大肠杆菌DNA和牦牛腹泻粪便样本提取的总DNA为模板,采用PCR方法扩增产肠毒素大肠杆菌黏附因子K99+菌毛基因片段,分析产肠毒素大肠杆菌在牦牛腹泻中存在情况,同时比较两种DNA提取方法对产肠毒素大肠杆菌PCR检出率的差异;以分离自外表健康牦牛粪便的105株大肠杆菌DNA为模板,采用PCR方法扩增产肠毒素大肠杆菌黏附因子K99+菌毛基因片段,比较牦牛源产肠毒素大肠杆菌在外表健康牦牛和腹泻牦牛中的携带情况.结果:从26份牦牛腹泻粪便样本中共鉴定出84个大肠杆菌菌落携带K99菌毛基因,这些菌落分别来自所有26份牦牛腹泻样品,因此,牦牛腹泻样本100%分离并检测到携带K99+菌毛基因的产肠毒素大肠杆菌;而粪便总DNA检测结果为K99+菌毛基因阳性率84.62%(22/26),粪便中提取的总DNA模板K99+菌毛基因PCR检出率略低于分离鉴定的细菌DNA检出率;105株外表健康牦牛粪便样本分离株中检测到携带K99+菌毛基因的产肠毒素大肠杆菌34株,检出率为32.38%(34/105),产肠毒素大肠杆菌在牦牛腹泻样本中的检出率显著高于外表健康牦牛粪便的检出率(P0.001).结果表明,产肠毒素大肠杆菌在牦牛粪便中存在广泛,是引起牦牛腹泻的一种重要病原菌;以粪便中提取的总DNA为模板,可快速检测牦牛粪便中产肠毒素大肠杆菌的存在.

Investigation of enterotoxigenic escherichia coli isolated from yak in northwest Sichuan Province

In order to investigate the enterotoxigenic Escherichia coil （ETEC） in yaks distributed in northwest Sichuan province, Escherichia coli （E. Coll.） is isolated from diarrhea or healthy-looking yak fecal samples collected from Ganzi and Aba prefectures in Northwest Sichuan province, and then total DNA extracted from diarrhea fecal samples or isolated E. CoB. DNA is used as template in PCR to amplify ETEC K99~ gene. ETEC K99~ gene positive rate is 84.62% （22/26） in the 26 yak diarrhea fecal sample total DNA, and 84 E.Coli. colonies isolated from 26 yak diarrhea fecal samples are identified as ETEC carrying K99＋ gene distributing in all 26 yak diarrhea fecal samples; 34 strains of ETEC containing K99＋ gene are identified in 105 E.Coli strains isolated from healthy-looking yak fbcal samples, the E. Coll. K99＋ gene positive rate is 32.38% （34/105）. The results show that ETEC exists in both yak diarrhea feces and healthy-looking yak feces, which is a major pathogen in yak diarrhea disease; total DNA extracted from diarrhea fecal samples can be used to rapidly identify ETEC in yak feces.