Analysis Of Drug Resistance And Molecular Genetic Analysis Of MRSA Isolated From Bovine In Some Farms In North Xinjiang

Staphylococcus aureus is the most common and most important pathogens causing dairy bovine mastitis.Recent years,more reports have been made on the isolation of methicillin resistant Staphylococcus aureus from milk and dairy products.The multipe-drug resistance(MDR)of MRSA has brought huge challenges to the clinical treatment of dairy mastitis.At present,MRSA not only resistant to all ? lactam antibiotics medication,but also appeared multidrug-resistance,thereby affecting the clinical treatment of dairy mastitis.In particular,ST398 type MRSA was recognized as human and livestock related MRSA,therefore isolating and identifing of bovine MRSA,analyzing the molecular epidemic of local MRSA strains,defining its drug resistant characteristics and evolution could provid theory basis for the proper use of antibiotics,and for the prevention and control of bovine mastitis MRSA.This study collected clinical and subclinical mastitis cow milk samples 947(Urumqi 209,Changji 210,Shihezi 223 and Yili 305)and dairy farm workers other groups samples 40 throat swab in northern Xinjiang and seperation and identification were perfored with these samples.The nuc and mecA gene were also amplified by PCR.There were 19 MRSA strains and 1 human MRSA were identified and the isolation rate was 2.1%.The antibiotic resistance of 19 strains from bovine and 1 MRSA from human were tested in this study.Our result showed that drug resistance rate of these MRSA strains to amoxicillin,ampicillin,ceftiofur,cefoxitin,penicillin,clindamycin,clarithromycin,norfloxacin,sulfadiazine sodium,erythromycin and tetracycline was higher than 60%.The drug resistance rate to Cefuroxime was up to 100%,The sensitivity to gentamicin and doxycycline were higher than 60%.These MRSA isolates showed dramatic multidrug-resistance.79% MRSA isolates could resistant to 10 and more than 10 kinds of drugs.Human MRSA isolate was sensitive to tetracycline and sulfamethoxazole and showed resistant to other drugs.Molecular genetic analysis of 19 bovine strains and 1 human MRSA strain were performed by multilocus sequence typing(MLST)and staphylococcal protein A(spa)typing.The seven kinds of genes tpi,yqiL,arcC,aroE,g1 pF,gmk and pta of the 20 MRSA strains were amplified and sequenced.Then their sequences were compared with the international database and analyzed.The results showed that 19 MRSA strains isolates belonged to 12 ST types.These ST types were ST2393(10.5%),ST188(5.3%)and ST97(5.3%)respectively.Among them,ST398(36.8%)was the mostly popular ST type.19 MRSA strains could be divided into 7 spa types,t034(n = 7)was the dominant spa type.t034(n = 7)was superiority spa type,followed by t189(n=3)and t4030(n=3).t267(n=2),t359(n =2),t114(n=1),and t7589(n=1).One human MRSA belonged to t034-ST398.In conclusion,this according to this study result,our result showed that bovine MRSA in Xinjiang mainly was ST398 type,spa type mainly was t034,and one human MRSA was ST398-t034.The ST398 and ST188 of found in this study were different from other precious report in our country.These 2 genotypes were correlated with the human MRSA and some relation with human.Which suggest there exist the trend of MRSA transmission between bovine and human.