Antimicrobial Resistance And Virulence Genes Of Methicillin Resistant Staphylococcus Aureus Isolated From Bovine Mastitis

Bovine mastitis is a common disease that causes the greatest hann to cows and the most serious economic loss.The emergence of methicillin-resistant Staphylococcus aureus brings great difficulties to clinical treatment.Therefore,the detection and analysis of antimicrobial resistance,resistance genes and virulence genes of bovine MRSA are useful to prevent and treat diseases caused by the pathogen,which has very important practical significance.The results:In this study,73 strains of MRSA were isolated from 303 strains of S.aureus,which come from cow mastitis milk samples and the resuscitation laboratory.Then,it was tested for drug susceptibility,drug resistance genes and virulence genes.The results of drug susceptibility test showed that the highest resistance rate of penicillin,gentamicin and kanamycin in 73 strains of MRSA,which performed complete resistance;followed by ciprofloxacin,levofloxacin,clindamycin,tetracycline and rifampicin.The detection of 73 MRS A resistance genes showed that tetM,aacA-aphD,rpoB,blaZ,norA,norB,norC,sepA,mepA,mdeA and other genes were contained in all MRSA;followed by tetK gene and qacA/B gene,etc.,the smr gene was not detected.The detection of 73 strains of MRSA virulence gene showed that among the 73 strains of MRSA,genes such as fnbA,clfA,clfB,cna,sdrE,Map/eap,seh,hla,hid and hlg-2 were detected.Followed by sdrC,sdrD,bbp,ebpS,seg,sei,sea,sen,seo,sent set,sec,lukED,lukSF,hlg,hlb and other genes.Genes such as tst,spa,sed,see,sej,lukM,eta,etb,and edin were not detected.Conclusion:(1)All of the MRSA have multi-drug resistance,and the drug resistance ranged mainly in p-lactams,quinolones,aminoglycosides,rifamycins,tetracyclines,lincosamides,etc.(2)In the detection of MRSA resistance genes,the drug resistance rate of the five antibiotics was higher,and it was consistent with the drug resistance phenotype,indicating that the drug resistance gene is one of the important factors for drug resistance.(3)MRSA strains all carry virulence genes,among which genes such as adhesion factors,enterotoxin and hemolysin are dominant,indicating that virulence genes are closely related to clinical symptoms caused by bacteria.