| Bovine mastitis is a common problem in the dairy farming industry,which affects the quality and yield of milk.It is also one of the main reasons for the decline in the reproduction rate of cows,which has a serious impact on the economy.Therefore,bovine mastitis is an important issue that people are very concerned about.Escherichia coli(E.coli)is one of the important pathogens causing bovine mastitis.At present,people still use antibiotics for traditional treatment,but the abuse of antibiotics has led to increased resistance of microorganisms to these antibiotics,and the quality of milk has deteriorated.The increase of antimicrobial resistance is a serious problem in human and veterinary medicine.The emergence of antimicrobial resistant pathogens affects the clinical treatment of infectious diseases in humans and animals and has a significant negative impact on global public health and the economy.Therefore,a feasible method to solve this problem is to identify the relevant genes of pathogenic bacteria,understand the treatment mechanism,and study the relationship between pathogenic bacteria-related drug resistance and genotyping and clinical treatment.The prevalence,antimicrobial susceptibility,virulence genes of Escherichia coli covered from clinical bovine mastitis in China.The aim of this study was to identify the E.coli isolated from bovine mastitis milk and investigate antimicrobial resistance and virulence genes.Raw milk samples(n=497)were collected from different sizes of farms in five dairy major-regions of China.E.coli were identified using specific 16S,universal 16S rRNA and rpoB gene sequencing.Total 92 isolates from all 497 samples were confirmed as E.coli,including 19 strains from Inner Mongolia Autonomous Region,19 strains from Hebei Province,24 strains from Shanghai,18 strains from Heilongjiang Province and 12 strains from Shandong Province.Of these,the resistance of E.coli was determined by MIC microdilution broth and CLSI after agar-containing culture,and its virulence genes were detected by PCR.Resistance testing of 92 strains found that 48 strains were resistant,of which the resistance rate to ampicillin was the highest,reaching 38 strains(41.3%),followed by piperacillin,tetracycline.There is a total of 37 drug-resistant phenotypes,32 of which are multi-drug resistant,up to 8 antibiotics,and two strains are simultaneously resistant to 8 antibiotics.Of the 92 isolates,a maximum of 90 carried the resistance gene gyrA,and 24 of the tetracycline-resistant strains carried the tetA gene;a total of 75 strains were tested to carry the eae gene,which was identified as EPEC and 57 strains carried the ipaH gene.The relationship between drug resistance and genotype of E.coli should be taken as the research direction in the future,so as to control the phenomenon of excessive drug use in dairy cow mastitis caused by E.coliThe phylogroup,O serogroups and intimin types of Escherichia coli covered from clinical bovine mastitis in China.The objectives of this study were to identify the genotypes of E.coli in mastitis milk from five provinces in China,and to assess the risk of these isolates.Raw milk samples(n=497)of mastitis were collected from five provinces in May and September 2017,and genotyping experiments were conducted by PCR.Of the 92 isolates,the phylogenetic grouping can be divided into 5 groups,namely B1(35.9%),A(31.5%),C(22.8%)and E(4.3%),and 5 other strains were not assigned.Among them,drug-resistant strains are the most in group B1,75 strains carrying the eae gene were detected and identified as EPEC strains.All of the 75 isolates which can be divided into 5 eae endotoxin groups,respectively,eae-?R-?2,eae-?,eae-?R,eae-vR-?2 and eae-?,and which were all firstly found in mastitis,previously only found in patients with diarrhea.Additionally,there are 65 strains of E.coli can be divided into 7 O serotypes,namely O121,O91,O22,O26,O128,O111 and O113.The results revealed that E.coli as an important pathogen of bovine mastitis,the relationship between E.coli antimicrobial resistance and genotyping should be followed as a key research direction to control the over-medication treatment and other phenomenon of mastitis cow caused by E.coli.Therefore,it is very important to control Escherichia coli growth and to prevent the pollution of milk during the transporting.In addition to strictly controlling the use of antibiotics,the government should also pay attention to the spread of disease-causing pathogenic microorganisms between humans and animals.The environment for raising cattle on pastures needs to be properly controlled.This is of great significance for food safety and reducing the economic losses of the dairy industry cause by Escherichia coli. |
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