西藏林芝地区腹泻藏猪源大肠杆菌mcr-1基因调查分析

Epidemiological Analysis of Colistin-resistant Gene mcr-1 in Escherichia coli from Diarrheic Weaned Piglets in Nyingchi of Tibet

本研究旨在调查藏猪腹泻源大肠杆菌mcr-1的流行情况。从舍饲藏猪养殖场53份腹泻样品中分离到102株大肠杆菌。采用Kirby-Bauer纸片扩散法进行药敏试验,利用PCR扩增多粘菌素耐药基因mcr-1,并对mcr-1阳性菌株扩增β-内酰胺酶耐药基因、喹诺酮类耐药基因、氨基糖苷类耐药基因、四环素类耐药基因(tetA和tetB)和磺胺类耐药基因和氯霉素类耐药基因。结果显示,102株大肠杆菌中mcr-1检出率为32.4%。mcr-1阳性菌株对氯霉素、四环素和氨苄青霉素的耐药性较高,分别为88.2%、86.3%和84.3%。mcr-1阳性菌株中β-内酰胺酶耐药基因blaCTX-M的检出率最高,为84.8%;喹诺酮类耐药基因中qnrS检出率最高,为45.5%;氨基糖苷类耐药基因中aac(6)-Ib检出率最高,为48.5%。四环素类耐药基因tetA和tetB检出率分别为39.4%和54.5%;磺胺类耐药基因sul1、sul2和sul3检出率分别为100%、97%和78.8%;氯霉素类耐药基因cmlA和floR检出率分别为72.7%和84.8%。结果说明藏猪腹泻源大肠杆菌mcr-1阳性菌株的多重耐药比较严重,可能会带来广泛的传播,从而威胁公共卫生安全。

To investigate the prevalence of colistin-resistant gene mcr-1 of Escherichia coli isolated from diarrheic weaned piglets in Tibet,a total of 53 diarrhea fecal samples were collected and 102 strains E.coli were isolated.Antimicrobial susceptibility testing was carried out using the Kirby-Bauer disk diffusion method.PCR was used to amplify the colistin resistant gene mrc-1 and mcr-1 positive strains were screened for other resistance genes,including beta-lactam resistance genes,quinolone resistance genes,aminoglycoside resistance genes,tetracycline resistance genes,sulphonamide resistance genes and chloramphenicol resistance genes.The results showed that 32.4%of E.coli harboured mcr-1 gene were detected in 102 strains of E.coli.The mcr-1 positive strains showed high resistance rate to chloramphenicol(88.2%),tetracycline(86.3%)and ampicillin(84.3%).The most prevalent beta-lactam resistance gene was blaCTX-M(84.8%).The most prevalent quinolone resistance gene was qnrS(45.5%).The most prevalent aminoglycoside resistance gene was aac(6)-Ib(48.5%).Two tetracycline resistance genes tetA and tetB were carried by 39.4%and 54.5%,respectively.Three sulphonamide resistance genes were carried by 100%,97%and 78.8%,respectively.Two chloramphenicol resistance genes were carried by 72.7%and 84.8%,respectively.In conclusion the multi-drug resistance of mcr-1 positive strains of E.coli from diarrheic weaned piglets in Tibet is serious,which may cause widespread and threaten public health safety.