江苏地区鸡源大肠杆菌的流行特征及耐药性调查

Prevalence and antimicrobial resistance of Escherichia coli isolated from layers and broilers in the Jiangsu area

对2022年在江苏省部分养鸡场不同周龄蛋鸡、肉鸡泄殖腔拭子样本中的大肠杆菌进行分离鉴定及常用抗菌药物的的耐药性调查,以了解江苏地区鸡源大肠杆菌的流行情况和耐药状况,为相关养殖场临床抗菌药物的合理使用提供参考。本试验通过增菌、麦康凯培养基选择培养、PCR鉴定等方法对鸡泄殖腔拭子样本中的大肠杆菌进行分离和鉴定,然后采用微量肉汤稀释法检测16种抗菌药物对分离菌株的最小抑菌浓度(MICs)。结果显示:试验共分离出167株大肠杆菌,分离菌株对四环素、氨苄西林、磺胺异噁唑和复方新诺明耐药程度较高,耐药率分别达82.63%、78.45%、72.46%和68.86%;对美罗培南较为敏感,耐药率低至0.6%;对其余9种药物的耐药率在20.36%~55.10%范围内,未分离出多黏菌素耐药菌株,多药耐药菌株耐药率高达84.43%。10~11周龄肉鸡分离菌对各抗菌药的耐药率明显大于16~29周龄和33~60周龄;而蛋鸡样品分离菌对各抗菌药的耐药率:44~82周龄>6~17周龄>31~42周龄,且44~82周龄的耐药率明显高于其他2个周龄段,提示规模化养殖场中低周龄肉鸡和高周龄蛋鸡的耐药性相对较为复杂,这可能与临床用药有关。另外,本研究表明,江苏省鸡源大肠杆菌对四环素、氨苄西林、磺胺异噁唑和复方新诺明抗菌药物的耐药情况较为严重,养殖场应基于药敏结果合理、谨慎使用抗菌药物,并在生产各环节中加强细菌耐药性的常规监测。

In order to understand the prevalence and antimicrobial resistance of Escherichia coli in layers and broilers in the Jiangsu area,the isolation and identification of Escherichia coli in cloaca samples of layers and broilers of different weeks of age in various chicken farms in Jiangsu were carried out in 2022 in order to provide reference for rational use of clinical antibacterial drugs in relevant chicken farms.In this experiment,Escherichia coli was isolated,purified and identified in cloacal samples from chickens by enrichment,selective culture on Mac-Conkey medium,PCR identification and other methods.Then,the minimal inhibitory concentrations(MIC)of 16 antibacterial drugs against the isolated strains were determined by microbroth dilution.The results showed that 167 strains of Escherichia coli were isolated in the study.The isolated strains were highly resistant to tetracycline,ampicllin,sulfamethoxazole and cotrimoxazole with the drug resistance rates of 82.63%,7845%,72.46%and 68.86%,respectively.The isolates were sensitive to meropenem,and the drug resistance rate was as low as 0.6%.The drug resistance rate to the other nine drugs ranged between 20.36%and 55.10%.No colistin resistant strains were isolated in this study,and the drug resistance rate of multidrug resistant(simultaneously resistant to three or more antibiotics)strains was as high as 84.43%.The antibiotic resistance rate of the strains isolated from broilers aged 10-11 weeks was significantly higher than that of the birds aged 16-29 weeks and 33-60 weeks.However,the resistance rate of the bacteria isolated from the layer samples to various antimicrobial agents:layers at 44-82 weeks of age>those at 6-17 weeks of age>those at 31-42 weeks of age;and the resistance rate of the chickens at 44-82 weeks of age was significantly higher than the other two groups at different weeks of age.This suggested that the resistance of the low-age broilers and the high-age ones in large-scale farms was relatively complex,which might be related to clinical medication.In addition,this study showed that the resistance of Escherichia coli from chickens in the Jiangsu area to tetracycline,ampicillin,sulfamethoxazole and compound sulfamethoxazole was relatively serious,and the farms should use antibiotics reasonably and cautiously based on the drug sensitivity results,and make greater endeavor in routine monitoring of bacterial resistance in all aspects of production.