Study On Antibiotic Resistance Analysis And Fluoroquinolone Resistance Genes Detection Of Staphylococcus Aureus Strains Isolated From Cow

Staphylococcus aureus (SA) is one of the most common pathogen in medical and veterinary clinic and causes many diseases of person and livestock. With the extensive and abuse application of antimicrobials, Staphylococcus aureus is resistant to all antimicrobials and has brought multiple drug resistance, which is serious clinical problem of anti-infective treatment of the veterinary. Therefore, it’s very important to analyze antimicrobials resistance and study on the molecular epidemiology of its resistance not only for disease prevention caused by Staphylococcus aureus but also for monitoring the development and spread of resistant strains.By microbiology and molecular biology methods, Staphylococcus aureus were separated and identified from1263clinical and subclinical types of cow mastitis samples, which were collected from the NingXia region cow farms. The results showed that227strains of Staphylococcus aureus were isolated and identified from1263samples, the isolation rate was17.97%. The16S rDNA and nuc gene were detected by PCR. The results showed that16S rDNA and the nuc gene of220strains Staphylococcus aureus were positive. The positive rate was17.42%. The accordant rate was96.92%by two kinds of detection methods.The susceptibility of220Staphylococcus aureus was determined by means of the methods of disk diffusion according to CLSI. The results showed that the highest resistances were penicillin and ampicillin and the resistance rates achieved83.18%. The resistance rate of ofloxacin, amoxicillin/clavulanic acid and ciprofloxacin was56.37%,51.82%and49.55%respectively. The lowest resistance rate was2.27%, which was meropenem. The other drugs resistant rates were7.27%-40.5%. But all staphylococcus aureus were sensitive to vancomycin. All isolates tolerated up to13kinds of drugs. The main resistance spectrum was6kinds of drugs and accounted for12.73%.The MRSA was determined by means of the methods of oxacillin disk diffusion. The results showed that2strains MRSA were identified and9strains were between resistant and sensitive. The mecA and femA gene of Staphylococcus aureus were amplified by PCR. Except to the mecA gene in positive ATCC33591bacteria of methicillin-resistant Staphylococcus aureus was amplified the target fragment, the mecA gene of2strains of220strains was positive and the detection rate was0.91%. At same time, femA gene of220Staphylococcus aureus were amplified and the positive rate was100%.The grlA, gyrA and norA gene of fluoroquinolone resistant gene were detected by PCR. The results showed that the detection rate of gyrA, norA and grlA was80%,78.18%and78.64%respectively. The part PCR products were sequenced. The sequencing results showed that the homology of grlA and gyrA were99%and the homology of norA was100%.In conclusion, we analysed drug resistance of Staphylococcus aureus isolated from the NingXia region cow farms and detected the fluoroquinolone resistance gene. From which we can uncover the resistance of Staphylococcus aureus in NingXia. Provide theory basis for using antimicrobials rationaliy and preventing and controlling the spread of drug-resistant pathogen and resistant genes.