Isolation Identification And The Whole Genome Sequencing Analysis Of A Extraintestinal Pathogenic Escherichia Coli From Sheep

Extraintestinal pathogenic Escherichia coli(Ex PEC)is an important zoonotic pathogen that causes both human and animal parenteral infections.Studies have shown that Ex PEC can cause meningitis,urethritis,peritonitis,pneumonia,sepsis and other diseases.At present,domestic and foreign reports show that the study of Ex PEC strains mainly focused on human,avian and swine sources,while the related research about sheep source Ex PEC has rarely been reported.In the spring of 2016,respiratory diseases have occurred in a large-scale sheep field in Yanbian area of Jilin Province,in fected sheep showed severe dyspnea.β-lactam drugs,tetracycline drugs were mainly used on the treatment of in fected sheep,but these sick sheep did not heal,more than 30 sheep have died and that caused great economic losses to the sheep field.In order to identify the pathogen causing the respiratory infection,three specimens of dead sheep were examined by routine biopsy and histopathological examination,and the pathogenfrom the lung tissues and nasal swab samples were isolated and identified.Drug susceptibility testing and the whole-genome sequencing analysis were performed,the experimental results are as follows:(1)There are clear lesion in the lungs of the dead sheep,lung interstitial widening,bronchial wall loss,edema,in addition to macrophages and neutrophils infiltration have shown by lung histopathological examination.The pathogenicity test was carried out with the pathogens isolated from the lungs,the results showed that the isolates had strong pathogenicity.The 16 S r DNA of the isolates was determined by molecular biology.The results showed that the 16 S r DNA sequence of the strain was 100% homologous to the E.coli sequence and the isolate were named E.coli-slyb.(2)The drug sensitivity test of E.coli-slyb was carried out by agar double dilution method,results showed that E.coli-slyb had different degrees of resistanceto10 commonly used antibiotics,include amikacin,streptomycin,spectinomycin,ciprofloxacin,norfloxacin,enrofloxacin,ampicillin,amoxicillin,chloramphenicol and cotrimoxazole,moderately sensitive to gentamicin,florfenicol,ofloxacin,only sensitive to doxycycline,cefotaxime,ceftriaxone,polymyxin B.(3)For a further exploration about the resistant genotype and virulence factors of E.coli-slyb,the whole genome of E.coli-slyb was sequenced by high-throughput sequencing.The analysis results of E.coli-slyb showed that the E.coli-slyb genome carried more than 10 resistant genes include blaACT-5,blaACT-9,blaCMY-20,blaCMY-87,blaCMY-84,blaCMY-80,blaCMY-7,bla CMY-98,tet(34)and dfr A3,can mediated to the drugs resistant of β-lactam drugs,tetracycline drugs,trimethoprim drugs resistant.There are 172 virulence genes in the genome of the isolate,include Escherichia coli-specific genes such as HlyE,FyuA,irp2 and eaeH,which proved that the isolated bacteria was Extraintestinal pathogenic Escherichia coli.