| Escherichia coli is a common bacterial disease in pigs,and it is one of the most important infectious diseases that seriously harm the safety of piglets.At present,the main means of preventing and treating this disease is the use of antibiotics,which has led to more and more serious drug resistance.Escherichia coli is an important commensal pathogen of human and animal.The emergence and widespread epidemic of animal-derived resistant bacteria not only seriously affects the sustainable and healthy development of livestock and poultry breeding,but also seriously threatens animal food safety and human health.In order to guide clinical scientific selection of antibiotics,it is urgent to monitor the clinical resistance of Escherichia coli in Henan,especially to study the distribution characteristics of floR,CTX-M and mcr-1,the main drug resistance genes of florfenicol,ceftiofur and myxobacterin.Therefore,this paper carried out a survey on the resistance of Escherichia coli in pigs in Henan Province.1.This study conducted a drug susceptibility test of 8 types of 13 antibiotics against 856 strains of Escherichia coli isolated from 2013 to 2018.The results showed that all strains had different degrees of drug resistance,and the resistance rate to tetracycline,doxycycline,sulfisoxazole,cotrimoxazole,and ampicillin was maintained at a high rate(about 90%);Drug resistance rates were:florfenicol(79.8%),spectinomycin(74.8%),enrofloxacin(45.6%),ofloxacin(32.2%),colistin(31.1%),Amoxicillin/clavulanic acid(30.0%),gentamicin(25.5%),ceftiofur(15.5%);resistance rate to colistin continued to increase from 2013 to 2015,reaching the highest in 2015(56.6%),starting to decline after 2015 until 0%in 2018.2.A multiplex PCR assay for the main drug resistance genes floR,CTX-M and mcr-1 of florfenicol,ceftiofur and colistin,which are commonly used in clinical Escherichia coli,was established.By optimizing the parameters of the multiplex PCR system,such as primers and annealing temperature,the sensitivity,specificity and repeatability of the method were investigated.The sensitivity of the method is 1.46x 105 CFU/mL,and it has high specificity and stability.The coincidence rate with single-plex PCR is about 98%.Compared with traditional single-plex PCR,the multiplex PCR technology is fast,efficient and practical.It provides a new technical means for detecting drug-resistant genes commonly used in E.coli.3.Using the established multiplex PCR detection method,the isolated 856 strains of E.coli major resistance genes floR,CTX-M and mcr-1 were detected.The results showed that the detection rate of floR gene was 67.9%(581/856),including 72.3%in Zhengzhou,84.9%in Kaifeng,82.3%in Xuchang,and 48.5%in Jiaozuo.The detection rate of CTX-M gene was 8.4%(72/856).Zhengzhou 2.1%,Jiaozuo 6.3%,Kaifeng 16.5%,Xuchang 15.7%;mcr-1 gene detection rate was 27.6%(236/856),including Zhengzhou 10.2%,Jiaozuo 7.2%,Kaifeng 45.6%,Xuchang 43.8%.The effects of drug habits in different regions on the distribution and prevalence of Escherichia coli resistance genes were analyzed,and the effects of drug habits in different regions on the distribution and prevalence of drug resistance genes were explored.Through the research of this subject,the clinical drug resistance of Escherichia coli in Henan Province from 2013 to 2018 was investigated,and the main drug resistance gene of florfenicol,ceftiofur and colistin,floR,was established in pig-derived E.coli.The multiplex PCR assay of floR,CTX-M and mcr-1 preliminarily grasped the distribution characteristics of E.coli floR,CTX-M and mcr-1 genes in Henan Province,and evaluated the risk resistance and clinical science of Escherichia coli in pigs.Provide reference for medication,and provide technical support for food safety,public health safety and ecological environment safety. |
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