Wang Haoju, Mao Xuhu, Ding Honglei, Zou Quanming, Peng Xiao
Key Laboratory of Grazing and Domestic Grazing Animals of Chongqing, College of Animal Science and Technology, University of Southwest, Chongqing 400715, China.
Vet Res Commun. 2008 Aug;32(6):449-61. doi: 10.1007/s11259-008-9048-8. Epub 2008 May 15.
Prevalence, presence of virulence and adherence associated genes, genetic diversity, biochemical characteristics, and antibiotic susceptibility were determined for Escherichia coli O157 isolated over 4 months in Chongqing city and Three-Gorge Reservoir Areas. 11 isolates of E. coli O157 were isolated from 1504 samples and 7 of them are O157:H7 and 4 are O157:H? All O157:H7 isolates had eaeA, ehxA, EspA and Tccp genes, but did not have stx1 and stx2. All O157:H? isolates did not have stx1, stx2, eaeA, ehxA, EspA and Tccp genes except for the isolate obtained from Yunyang county which had stx1. When eaeA and ehxA presented in isolates were digested by restriction enzymes, the numbers and the sizes of the segments were the same as the control E. coli O157 strains. This suggests that eaeA and ehxA exhibit poor polymorphism. Most E. coli O157 isolates showed identical biochemical activities to the standard strains for sorbitol and rhamnose, and all E. coli O157:H7 obtained from feces at the same dairy cattle farm had similar biochemical characteristics. Antibiotic susceptibility demonstrated resistance of the isolates to penicillin, ampicillin, bacitracin, cefuroxime, erythromycin, gentamycin and tetracycline, indicating the isolates obtained in this study had a multi-drug resistance.
对重庆市和三峡库区4个月内分离出的大肠杆菌O157进行了患病率、毒力和黏附相关基因的存在情况、遗传多样性、生化特性及抗生素敏感性测定。从1504份样本中分离出11株大肠杆菌O157，其中7株为O157:H7，4株为O157:H?。所有O157:H7分离株都有eaeA、ehxA、EspA和Tccp基因，但没有stx1和stx2。除从云阳县分离出的菌株有stx1外，所有O157:H?分离株都没有stx1、stx2、eaeA、ehxA、EspA和Tccp基因。当分离株中的eaeA和ehxA用限制性内切酶消化时，片段的数量和大小与对照大肠杆菌O157菌株相同。这表明eaeA和ehxA表现出较差的多态性。大多数大肠杆菌O157分离株对山梨醇和鼠李糖的生化活性与标准菌株相同，并且从同一奶牛场粪便中获得的所有大肠杆菌O157:H7具有相似的生化特性。抗生素敏感性表明分离株对青霉素、氨苄青霉素、杆菌肽、头孢呋辛、红霉素、庆大霉素和四环素耐药，表明本研究中获得的分离株具有多重耐药性。
