河南省新发传染病EHEC O157：H7监测研究

STUDY ON EMERGING INFECTIOUS DISEASES OF EHEC O157︰H7 IN HENAN PROVINCE

[目的]了解河南省肠出血性大肠杆菌(EHEC)感染性腹泻的发病情况、宿主带菌状况、食品污染程度及志贺毒素(stx)基因型,为制订有效的防治对策提供依据。[方法]采集河南省监测点腹泻病人、家畜、家禽粪便,水和肉食品等标本分离EHEC菌株,应用分子生物学技术检测分析菌株rfbO157、rfbO111、hlyA、eaeA、stx2和stx1等毒力基因和突变基因。[结果](1)从腹泻病人、家畜、家禽、食品、水、蜣螂和苍蝇中均分离出EHEC菌株共275株,总分离率7.88%;其中O157︰H7菌株为232株(84.36%),携带stx2基因EHECO157︰H7菌株88株(37.93%);非O157︰H7菌株43株(15.64%)。(2)宿主动物中羊带菌率最高(6.96%),是河南省EHEC最主要宿主动物;多重PCR检测出8种不同毒力基因组合型,主要为rfbO157+、hlyA+、eaeA+、stx2+组合。stx2变种毒素GK探针检测出3种毒素变种杂交带型,其中stx2原毒素+stx2vha型占7.4%,stx2vha型的占72.2%,未知新杂交带型占20.4%。(3)EHECO157︰H7菌株可分为9个PFGE型,自羊、牛、鸡和蜣螂和腹泻病患者中分离的携带stx2vha菌株同属一个PFGE型。(4)144株不携带志贺毒素的O157菌株中发现O157︰H38、O157︰H42和O157︰Hund(未确定型)新菌株。[结论]河南省家禽、家畜中普遍携带EHECO157︰H7大肠杆菌,羊是最主要的宿主动物;EHECO157︰H7为我省优势菌型,其毒素基因型为stx2-eaeA-hlyA并以stx2vha亚型为主。EHEC在外环境中污染严重并可在人与人、动物与人之间传播,家畜、家禽携带stx2 EHECO157︰H7率的高低与EHEC人群感染发病呈相关关系。

[ Objective] To find out the status of infectious diarrhea of EHEC as well as its carrying status in livestock and poultry, the status of food contamination and the carrying genotype of Shiga toxin （stx）. [Methods] EHEC strains were isolated from stools of diarrhea cases, livestock and poultry, and samples of meat and water in surveillance areas of Henan Province. The toxic factors of rfbO157, rfbO111, hlyA, eaeA, stx2, stx1 and mutation subtype of Shiga toxin genes were tested with molecular biology technique. [Results] h total of 275 EHEC O157 ： H7 isolates were obtained from diarrhea cases, domestic animal, poultry and also from meats, water, flies and dung beetles. The total separation rate of EHEC was 7.88%. 232 of 275 isolates were O157 ： H7 （84.36%） and 88 of them carried stx2 gene （37.97%） . 43 of non O157 EHEC isolates were obtained （15.64%） . The separation rate of EHEC O157 ： H7 from goats was the highest （5.94%）; while the goats were the most common host animals carrying O157 ： H7 in Henan Province. All the strains were divided into 8 toxic genotypes by multiplex PCR and the main genome consist of stx2-eaeA-hlyA. Three different mutation subtypes were determined by hybridization test with GK probe, which included stx2vha subtype （72.2%）, stx2 and stx2vha （7.4%） and unknown new subtype （20.4%） . All of the EHEC O157 ： H7 isolates were divided into 9 PFGE types, the strains carrying stx2vha toxin gene from goats, cattle, chickens, dung beetles and diarrhea cases were the same PFGE type. O157 ： H38, O157 ： H42 and O157 ： Hund were found from isolates without stx2 [Conclusion] Most of the domestic animal and poultry in Henan Province can7 EHEC O157 ： H7, among them goats are the main host animal： EHEC O157 ： H7 is the main serotype, its toxin genome is stx2-eaeA-hlyA; while the main toxin genotype is stx2vha subtype. Environment contaminated by EHEC is severe, and EHEC could spread among human and animals; moreover, there is a positive correlation between the infectious diarrhea cases of EHEC O157 ： H7 and the carrying status of EHEC O157 ： H7 with stx2 in cattle and poultry.