上海市闵行区猪场中大肠杆菌 O157：H7的分离鉴定及生物学特性研究

摘要

To investigate epidemiology of Escherichia coli (E. coli) O157:H7 in pigs in Minhang district of Shanghai, E. coli O157:H7 was isolated on enrichment and selective media and identified by PCR and serum agglutination assay. The E. coli O157:H7 isolates were also tested for their biochemical characteristics, antibiotics susceptibility and major virulence genes. As a result, two E. coli O157 isolates were obtained from 280 samples collected from three pig farms. These two isolates possessed the same biochemical characteristics as O157:H7. As shown in PCR assay, isolate EHEC01 harbored Shiga toxin gene stx1 and Intimin encoding gene eae and isolate EHEC02 had only gene eae. In antibiotics susceptibility testing, these two E. coli O157:H7 isolates showed multiple resistance to most of 24 tested antibiotics, including beta-lactam, aminoglycosides, tetracyclines, chloramphenicol, quinolones and macrolides. Multiple drug resistance of E. coli O157: H7 isolates suggests the necessity of reinforcement of reasonable use of antibiotics on pig farms.%　　为了解上海地区猪场中大肠杆菌 O157：H7的流行情况，采用增菌、选择性培养基筛选、PCR 和血清型鉴定方法分离鉴定大肠杆菌 O157：H7，然后利用 PCR 方法检测菌株的毒力因子，应用药敏纸片法进行药敏试验。结果从上海地区不同猪场的280份样品分离得到2株肠出血性大肠杆菌 O157：H7，检出率为0.71%，生化试验表明该菌株与大多数 O157：H7特性相同。毒力因子检测表明，其中1株携带志贺毒素基因stx1和紧密素基因eae，而另株分离株仅检测出毒力基因eae。药敏试验结果显示，这2株大肠杆菌 O157：H7分离株对β-内酰胺类、氨基糖苷类、四环素类、氯霉素类、喹诺酮类、大环内酯类的24种抗生素有多重耐药性，耐药率为62.5%。因此，大肠杆菌 O157：H7在闵行区的猪群中存在，且具有多重耐药性，提示应关注畜牧养殖业中抗生素的科学使用。