Molecular Epidemiological Investigation of Escherichia Coli from Cow Mastitis in 2020 in Some Areas of China
To investigate the prevalence and characteristics of Escherichia coli mastitis of dairy cows,136 milk samples were collected from 11 provinces of China for bacterial isolation using PCR phoA amplication.The antibiotic sensitivity of all isolates was tested by the Kirby-Bauer disk diffusion method and their virulence genes were tested by the triplex PCR method.Then,phylogenetic analysis were performed for these isolates according to the genes of chuA,yjaA and TSPE4.C2.The results showed that 61(44.85％)E.coli isolates were obtained from 136 samples.These E.coli isolates had varying resistance to cefradine(37.70％),ampicillin(32.78％)and tetracycline(26.22％).The virulence genes were also detected at different rates,such as ompA(98.36％),traT(75.40％),CNF1(54.09％),irp2(47.54％),iucD(32.78％),sitD(14.75％)and chuA(13.11％).No isolates had ST2 and hlyA.In addition,grouping of these 61 E.coli isolates presented different results,such as 67.21％strains in group A,19.67％in group B1,8.19％in group D,and 4.91％in group B2.Groups A and B represented the main epidemic groups causing the clinical mastitis.Taken together,this study would provide a reference for the prevention and control of the E.coli cow mastitis.
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