Antimicrobial Resistance And Molecular Epidemiology Of The Staphylococcus Aureus From Cow

Recently years,bacterial resistance has become a hotly debated topic in the world.The emergence of resistant strains of Staphylococcus aureus has attracted the attention of researchers around the world.Its appearance has led to the clinical treatment of humans and animals.Which becoming harder and harder,and it has caused huge economic losses.At present,the most effective drugs for the prevention and treatment of diseases caused by Staphylococcus aureus are still antibiotics.However,due to the unreasonable use of antibiotics,more and more drug-resistant bacterias and drug resistance genes have emerged,giving clinical treatment belts.A great deal of troubles and challenges have appeared.In order to understand the epidemiological characteristics of Staphylococcus aureus in some areas of China and its resistance status and the carrying status of drug resistance genes,81 strains of staphylococcus aureus were isolated and identified from milk samples which isolated from some large-scale dairy farms in the Guangdong and Gansu province of China,and we have done the drug sensitivity test,drug resistance gene identification and genotyping test.serial results were carried out in this paper:To isolate and identifiy of Staphylococcus aureus.after enrichment,purification and culture of the bacterias in the milk samples which separated from some large-scale dairy farms in the s Guangdong and Gansu province,we use the common 16 S r RNA primers of the bacterias and the specific genes of Staphylococcus aureus heat-resistant nuclease gene nuc and VITEK-2-COMPACT15 automated microbial identification system for species identification of isolates.The results showed that 81 strains of Staphylococcus aureus were isolated,among which 57 strains were isolated from the south and 24 from the north.Among 81 strains of Staphylococcus aureus,MIC susceptibility test and susceptibility test revealed that MRSA contained 20 strains(24.7%)and MSSA contained 61 strains(75.3%).The resistance rates to the remaining antibiotics from high to low were: florfenicol(80.2%),penicillin(66.7%),ciprofloxacin(33.3%),erythromycin(32.1%),kanamycin(25.9%),ampicillin(25.9%),clindamycin 24.7%,ceftiofur(6.2%),oxacillin(4.9%),gentamicin(2.5%),cefazolin(2.5%),vancomycin(0),tetracycline(0),linezolid(0).And there were 16 strains resistant to 3 drugs,5 strains resistant to 4 drugs,7 strain resistant to 5 drugs,and there were 6 strains resistant to 6 drugs,1 strain resistant to 7 drugs,1 strain resistant to 8 drugs,2 strain resistant to 9 drugs,and there were 2 strains resistant to 10 drugs.The detection rate of drug resistance genes from high to low was: aac(6)/aph(2")(100%),fem A(100%),erm B(100%),van B(100%),tet M(100%)),flo R(80.2%),erm C(77.8%),fex A(50.6%),mec A(24.7%),tet A(0),tet C(0),nor(0),van A(0),van C(0).It was found that they were all demonstrated at least 5 kinds of drug resistance genes,and the positive rate of drug resistance genes is high.The drug susceptibility test and drug resistance gene analysis were performed on 81 strains of Staphylococcus aureus.All of Staphylococcus aureus were classified by spa and MLST typing techniques.20 strains of MRSA were classified by SCCmec.A total of 14 ST types,20 spa types and 5SCCmec types were found.Among them,4 strains of MRSA strains were identified as ST9-SCCmec IVb-t899 strains,which were relatively dominant types,and 9 strains of MRSA strains were identified as ST398-SCCmec I-t034,ST398-SCCmec IVc-t034,ST398-SCCmec V-t034,respectively.ST1-SCCmec I-t114,ST2632-SCCmec III-t091,ST398-SCCmec III-t8617,ST398-SCCmec III-t034,ST692-SCCmec III-t2247,ST188-SCCmec III-t189,and 7 SCCmec type III MRSA did not receive MLST and spa points types are presumed to be novel types,and the above types are more dispersed,which may be due to the increasing abuse of antibiotics resulting in increased resistance to Staphylococcus aureus.Combined with the above MLST and spa classification results,the dominant type of MRSA was found to be ST9-t899,and the dominant type of MSSA was ST398-t034;the dominant type of Guangdong was ST9-t899,the dominant type of Gansu was ST398-t034.A total of 1PVL gene-positive strain was detected in this study,and the carrier rate was 1.2%.MSSA,MLST,and spa type were ST1289-t16824,which were isolated from Gansu.An intensive research was done for the epidemiological characteristics,drug resistance,the status of carrying drug resistance genes and genotyping of Staphylococcus aureus,which has an important guiding significance for the rational use of antibiotics in the future.