Isolation,Identification And Partial Biological Characterization Of Escherichia Coli Of Equine Origin From Some Regions Of Xinjiang

Escherichia coli can be spread through a variety of means,including contaminated environment,water or food.E.coli infection in horses can cause diarrhea,abdominal pain,and dehydration,with some horses exhibiting muscle tremors,and severe infection can lead to death.At present,the main treatment method for equine E.coli disease is antibiotic therapy,and with the long-term extensive use of antibacterial drugs,pathogenic E.coli presents multiple drug resistance,and its drug-resistant factors can be transmitted between humans and animals,posing a greater threat to human health and healthy production of animal husbandry.Therefore,in this study,fresh horse manure samples were collected from horse farms in some areas of Xinjiang,and it was proposed to investigate the carriage of equine-derived E.coli in some areas of Xinjiang,and to detect its phylogenetic subgroups,biofilm-forming ability and related virulence and drug resistance genes.In order to further understand the prevalence of pathogenic E.coli in the region and provide experimental data for rational clinical use and prevention of equine diarrheal disease.1.A total of 56 fresh horse fecal samples were collected from four horse farms in Yili（n=38）,Hami（n=3）,Tacheng（n=5）and Altay（n=10）,Xinjiang,and 41 E.coli strains were isolated and identified by bacterial culture,Gram staining microscopy,biochemical tests and bacterial 16S r RNA sequence comparison,with an isolation rate of 73.2%（41/56）.2.Phylogenetic grouping,virulence gene detection and mouse pathogenicity tests were performed on the 41 isolated E.coli strains.The results showed that the phylogenetic groups of the 41 E.coli strains were dominated by group B1 70.7%（29/41）and group A 22.0%（9/41）.Five virulence factors were detected,and the highest detection rate was 87.8%（36/41）for the fim C gene,followed by 58.5%for fyu A,41.5%for irp2,36.6%for sep A,and 21.6%for hly F.Four strains of E.coli carrying different virulence genes were selected for mouse pathogenicity assay,and the results showed that the strains carrying virulence genes of HPI virulence islands（irp2,fyu A）were more pathogenic and may have potential pathogenicity.3.The obtained strains were subjected to drug resistance gene detection,drug sensitivity test and biofilm formation ability analysis.A total of eight resistance genes were detected,namely par C,gyr A and gyr B all 100.0%（41/41）,sul2 31.7%（13/41）,flo R 22.0%（9/41）,bla _TEM22.0%（9/41）,bla _CTX12.2%（5/41）and aad A 2.4%.The results of drug sensitivity tests showed that E.coli isolates were more sensitive to cefoxitin,chloramphenicol,gentamicin,imipenem and norfloxacin,and showed varying degrees of resistance to erythromycin,cefothiophene,cotrimoxazole,tetracycline and minocycline,with a multi-drug resistance rate of 70.0%.The results of biofilm formation assay showed that 39 of 41 E.coli strains had the ability to produce biofilm,17.1%（n=7）had moderate film forming ability,78.1%（n=32）had weak film forming ability,and 4.9%（n=2）had no detectable biofilm forming ability.In conclusion,E.coli populations of horse origin in some areas of Xinjiang are diverse,carrying multiple virulence genes and drug resistance genes,showing multiple drug resistance,and the results of the study explore the prevalence of E.coli in the region,provide experimental data for the rational clinical use of drugs and prevention of equine diarrheal disease,suggesting that the prevention and control of E.coli disease of horse origin should be strengthened clinically.