河南省肠出血性大肠杆菌(EHEC O157:H7)感染之流行与基因特征研究

目的 :了解河南省肠出血性大肠杆菌 (enterohemorrhagicescherichiacoli,EHEC)的流行状况与流行菌株的志贺毒素基因型。方法 :采集河南省 14个监测点上腹泻病人、家畜家禽粪便和肉食品等标本分离E HEC菌株。应用分子生物学技术检测EHEC菌株的rfbO157、rfbO111、hlyA、eaeA、stx2 和stx1等毒力基因和志贺毒素基因亚型 ,应用细胞培养技术检测菌株Vero细胞毒性。结果 :从腹泻病人、家畜家禽、肉食品、苍蝇、蜣螂中均分离出EHECO15 7:H7菌株 ,波尔山羊的带菌率最高达到 2 9.8%。 13 8株携带志贺毒素基因的菌株中 ,EHECO15 7:H7计 95株 ,占产毒菌株的 68.8% ;EHEC非O15 7菌株 43株 ,占 3 1.2 %。菌株可分为 5种毒素基因型 ,EHECO15 7:H 7仅含stx2 基因 ,以stx2 vha亚型为主 ,不含有stx1基因。EHEC非O15 7血清型毒素基因型较复杂。携带stx1和 /或stx2 的菌株均具有Vero细胞毒性。结论 :河南省腹泻病人和家畜家禽中存在EHEC感染。EHECO15 7:H7血清型是优势菌型 ,羊是主要宿主动物。目前河南省EHECO15 7:H7菌株毒素基因型为stx2 并以stx2 vha亚型为主。

A study on the epidemic status and the gene characteristics of EHEC O157:H7 in Henan Province

Objective: To understand the epidemic status of EHEC as well as the gene type of shiga toxin of the epidemic strains. Methods: EHEC strains were isolated from stools of diarrhea cases, and stools of domestic animal and domestic fowl, and samples of meat food in 14 surveillance areas and then their toxic factor rfb 0157, rfb 0111, hlyA, eaeA, stx 2, stx 1 and subtype of Shiga toxin genes were tested with molecular biology technique; Vero toxicity was tested with cell cultures technique. Results: EHEC O157:H7 strains were isolated from samples of diarrhea cases, and samples of domestic animal and domestic fowl as well as meat food, flies and Dung Beetles. The carrying rate of Boer goat was as high as 29.8%. Of the 138 strains with shiga toxin genes 95strains of EHEC O157:H7 were found, which made up 68.8% of the toxin-producing strains. 43 strains of non O157 EHEC were found which made up 31.2%. All the strains were divided into 5 types of toxic genes. EHEC O157:H7 only contained stx 2 gene mainly subtype of stx 2vha, without stx 1. The toxic gene type of the non O157 EHEC is rather complex. The strains with stx 1 and /or stx 2 all have the Vero toxicity. Conclusion: There are such diarrhea cases, and domestic animal and domestic fowl infected with EHEC in Henan Province. The dominant serum type is EHEC O157:H7 and the sheep is the main host animal. Currently shiga toxin genotype of EHEC O157: H7 strains is stx 2 and mainly the subtype of stx 2vha.