广州市农贸市场猪肉源伦敦沙门菌的流行情况及耐药性分析

Characterization of Prevalence and Antimicrobial Resistance of Salmonella Enterica Serovar London from Markets in Guangzhou

本研究旨在探究广州市2016年5-10月农贸市场猪肉源伦敦沙门菌的流行和耐药情况。从广州市农贸市场采集样品198份,分离得到28株猪肉源伦敦沙门菌,用K-B法测定其对18种抗菌药物的耐药性,用PCR方法鉴定其所携带的耐药基因。结果表明,市场猪肉样品中沙门菌的阳性率为74.2%(147/198),伦敦沙门菌的分离率为19%(28/147),其对磺胺异唑、四环素的耐药率分别为78.6%和75.0%;其次为链霉素、复方新诺明、氨苄西林、庆大霉素、氯霉素和氟苯尼考,耐药率依次为71.4%、67.9%、67.9%、67.9%、46.4%和42.8%;对萘啶酸(3.6%)和多黏菌素B(3.6%)耐药水平较低。有71.4%(20/28)的菌株对3种及3种以上抗菌药物耐药。氨基糖苷类耐药基因检出率为100%,aadA2(7.1%)、strA(37.9%)、aadB(100%);酰胺醇类耐药基因检出率为42.6%,cat1b(39.3%)、floR(39.3%);磺胺类耐药基因检出率为67.9%,sul1(60.7%)、sul2(60.7%);四环素类耐药基因的检出率为78.6%,均同时携带tetA和tetB;β内酰胺类耐药基因blaTEM检出率为10.7%;喹诺酮耐药基因qnrA、oqxAB和aac(6’)-lb-cr检出率为3.6%、10.7%和7.1%;黏菌素耐药基因mcr-1检出率为3.6%。伦敦沙门菌在广州农贸市场猪肉中是主要流行血清型之一,其对传统抗菌药物磺胺异唑、四环素、链霉素、复方新诺明、氨苄西林等耐药性严重,携带多种耐药基因,且具有多种多重耐药表型。这提示人们需要对市场沙门菌进行常态化检测与监测,加强对抗生素使用的监管,确保公共卫生和食品安全。

This study aims to explore the prevalence and drug resistance of Salmonella London from pork at the market in Guangzhou from May to October 2016.One hundred and ninety-eight samples were collected from the market in Guangzhou.Twenty-eight strains of S.London from pork were isolated.The KB method was used to test the drug resistance,and the drug-resistant genes were identified by PCR.The results showed that the positive rate of Salmonella from pork was 74.2%(147/198),the isolation rate of S.London was 19%(28/147).The drug sensitivity test of S.London showed that they were resistant to sulfisoxazole(78.6%)and tetracycline(75.0%),followed by streptomycin(71.4%),compound sulfamethoxazole(67.9%),ampicillin(67.9%),gentamicin(67.9%),chloramphenicol(46.4%)and florfenicol(42.8%),respectively.Also,the antibiotic resistance to nalidixic acid(3.6%)and polymyxin B(3.6%)is rare.And 71.4%(20/28)of the strains were resistant to three or more antimicrobial agents.The detection rate ofβ-lactam resistance gene blaTEM is 10.7%;the detection rates of quinolone resistance genes qnrA,oqxAB and aac(6’)-lb-cr are 3.6%,10.7%and 7.1%,respectively.Only 3.6%of the isolates carried colistin resistance gene mcr-1.It was found that S.London was one of the major epidemics in pork from markets in Guangzhou.It is highly resistant to traditional antimicrobials such as sulfisoxazole,tetracycline,streptomycin,compound sulfamethoxazole,ampicillin,carrying multiple drug-resistant genes,and has multi-drug resistant phenotypes.These results suggest that we need to conduct normalized detection and monitoring of Salmonella in the market,strengthen the supervision of the use of antibiotics,and ensure public health and food safety.