山东省微山县动物粪便中产志贺毒素大肠埃希菌血清型鉴定及耐药性分析

Serotype identification and antibiotic susceptibility of Shiga toxin-producing Escherichia coli in the Weishan area in Shandong Province, China

目的分析山东省微山县动物粪便中的产志贺毒素大肠埃希菌（STEC）的血清型及耐药状况。方法于2015年9月，采集山东省微山县共500份新鲜动物粪便样本（猪粪便145份，牛粪便140份，羊粪便130份，鸡粪便61份，鸭粪便10份，狗粪便8份，鹅粪便6份），从中共分离出16株STEC。采用血清凝集试验对STEC分离株进行血清分型，采用抗菌药物敏感性试验探讨其药敏性及耐药性。采用PCR方法检测四环素类耐药基因（tetA、tetB、tetC、tetD）以及β-内酰胺类耐药基因（blaSHV-1、blaCTX-M、6如删）共7种耐药基因。结果16株STEC中，13株来自猪粪便样本，2株来自牛粪便样本，1株来自羊粪便样本。O157：H7型STEC为2株，非O157型STEC为14株；非O157型STEC的血清型分布较为分散。在检测的16种抗生素中，对萘啶酸、磺胺异噁唑、复方磺胺甲噁唑、强力霉素、阿奇霉素、四环素、链霉素、氯霉素等8种抗菌药的耐药率分别为12／16、11／16、11／16、9／16、9／16、9／16、8／16、8／16，对萘啶酸耐药率最高（12／16），其次为磺胺异噁唑和复方磺胺甲噁唑（11／16、11／16），对头孢吡肟、亚胺培南均不耐药。16株STEC中15株出现了多重耐药性，其中三重耐药菌株5株，四重、五重耐药菌株各4株，六重、七重耐药菌株各1株。16株分离菌株中共检测出3种耐药基因，分别为tetA、tetB、tetC。结论从微山县分离出的STEC菌株血清型多样且分布较为分散，对常见抗生素具有多重耐药性，血清型复杂性及出现多重耐药性可能与菌株变异有关。

Objective To determine the serotypes and drug resistance profiles of Shiga toxin-producing Escherichia coli （STEC） in animal stools from the Weishan area in Shandong Province, China. To provide the basis for further study. Methods Five hundred animal stool samples （from pigs, cattle, sheep, dogs and birds） were collected from the Weishan area and STEC strains were isolated from these samples. Strains were serotyped by a serum agglutination test, and their drug resistance profiles were determined through antimicrobial sensitivity experiments. In this study, PCR was used to detect tetracycline resistance genes （tetA, tetB, tetC, tetD） and beta-iactam resistance genes （blaSHV-1, blaCTX-M, blaTEM）. Results Sixteen strains of STEC were isolated from animal stool samples. Thirteen strains were isolated from pig stool samples, two from bovine stool samples and one from a sheep stool sample. Two of the strains were identified as E. coli O157：H7, and other 14 strains were non-O157 STEC of different serotypes. Antimicrobial sensitivity experiments showed that 15 of the strains were muhidrug resistant. The rates of resistance were as follows： nalidixic acid （12/15 strains）, sulfisoxazole （1 1/16）, trimethoprim and sulphame-thoxazole （1 1/16）, doxyeycline （9/16）, azithromycin （9/16）, tetracycline （9/16）, chloramphenicol （8/16） and streptomycin （8/16）. Therefore, nalidixic acid showed the highest rate of resistance among the strains, followed by trimethoprim and sulphame-thoxazole, and sulfisoxazole. Resistance to cefepime or imipenem was not detected. In total, three types of drug resistance genes （tetA, tetB and tetC） were detected ong the 16 strains. Conclusion The results showed that STEC strains isolated from animals in the Weishan area were of a range of serotypes. The 16 strains of STEC isolated from animal stools in this area re resistant to a number of antibiotics, with many strains displaying muhidrug resistance.