| In China,the pork is the major meat and original materials of meat products.With the widespread use of antibiotics in disease prevention and fodder supplementation,the increasing prevalence of resistance isolates among Escherichia coli from swine became an emerging problem.Meanwhile,the large-scale use of antibiotics has led to the establishment of a repository of E.coli strains of pigs that can produce drug-resistance genes,which can spread pigs and contaminate pork to humans through the food chain,causing serious food safety and public health problems.In this study,a total of 147 samples were collected from the diarrhea piglets,healthy piglets,and pigsty environment in a pig farm in Guangzhou.The samples were isolated and identified according to GB 4789.6-2016,and the disc diffusion method(K-B)was used to test 11 kinds of antibiotic susceptibility of E.coli isolates from swine.Polymerase chain reaction(PCR)methods,to detect drug resistance genes of drug resistant E.coli,the binding transfer assay was used to explore the level of E.coli resistance.The details are as follows:1.The separation rate of a total of 147 samples is 78.23%.The separation rate of the E.coli was 85.57% on samples from diarrhea piglets of feces,nasal swabs,and so on.The separation rate of the E.coli was 89.29% on samples from healthy piglets of feces,nasal swabs,and so on.The separation rate of the E.coli was 78.23% on samples from the ground environment of pigsty,drinking water,and fodder.2.By the K-B method,the E.coli isolates in the study were tested for susceptibility to 11 drugs.All the E.coli strains were resistant to sulfamethoxazole and the resistance rate was nearly 100%.The fluoroquinolones antibiotic,levofloxacin Gatifloxacin and ciprofloxacin had higher drug resistance rates,which is 53.91%(62/115),48.70%(56/115),and 36.52%(42/115),respectively.Additionally,the proportion of multidrug-resistance isolates was 46.09%(53/115).All strains were sensitive to meropenem.3.The PCR results of resistant genes showed that the detection rate of tetracycline gene tetM detected in this experiment was the highest,and the detection rate was 100%.The genes of aac(3')-Ib,aac(3)-IIb,blaTEM,ant3''-Ia,blaCTX and sul1 were 84.62%,84.62%,73.81%,73.08%,61.90% and 54.39,respectively.The detection rates of quinolone-resistant genes of qnrB,qnrS and aph(3')-IIa were low,was 6.35%,14.29% and 38.46%,respectively.In this experiment,qnrA gene and tetK gene were not detected in all isolates.4.53 strains of multidrug resistant E.coli isolates were transferred by conjugation.Thirtynine isolates successfully transferred resistant plasmids to the recipient strain E.coli J53.The conjugates were tested for susceptibility to quinolones,?-lactams and other five antibiotics.PCR was used to detect the drug-resistance genes carried by the transconjunction.The results showed that the antibiotic resistance level and the resistance gene of the conjugate were significantly lower than that donor strain.In this study,pig-derived E.coli strains from a pig farm were tested for their resistance to ?-lactams,quinolones,and aminoglycosides,and the distribution of drug-resistance genes that can guide the prevention and treatment of diarrhea in piglets.Further support for the prevention and control of outbreaks of food-borne diseases. |
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