Analysis Of Drug Sensitivity Of Staphylococcus Isolated From Bovine Mastitis And Partial Drug Resistance Genes In Partial Regions Of Jiangsu Province

Bovine mastitis is one of the common diseases in dairy herds, and has caused huge economic losses. Pathogen infection is the major cause of bovine mastitis. To know the state of bovine mastitis and its agents in partial regions of Jiangsu province, mastitis milk samples were collected from five dairy farms in three regions of Jiangsu province, and pathogenic agents were isolated. And drug sensitive of Staphylococcus isolates and partial drug resistance genes were analyzed.Part1:Investigation of pathogen of bovine mastitis in partial regions of Jiangsu provinceThe610milk samples were collected from five dairy farms. The bacterial isolates were identified with biochemical identification and16S rDNA PCR. At a test dairy farm, milk samples were collected from November2012to October2013, and the incidence of mastitis were monitored with the BMT. The results showed that, the average incidence of bovine mastitis was31.2%. The average incidence of clinical mastitis was7.2%, and the average incidence of subclinical mastitis was24.1%. In Jiangsu Province, the major pathogen of bovine mastitis is Staphylococci, accounting for47.8%and Staphylococcus aureus isolated was20.0%, CNS separation rate was27.8%. Second pathogen was Streptococcus, accounting for28.9%. The results indicated that Staphylococcus might be the major pathogenic bacteria in Jiangsu province.Part2:Drug resistance testing of Staphylococcus from bovine mastitisIn this study we did susceptibility testing against383strains of Staphylococcus used K-B method with selected20kinds of drugs (8Classes) for Staphylococcus. The results showed that the multi-drug resistant to Staphylococcus was common, and more than4-fold resistant strains of drugs accounted for60.1%. The drug resistance rates of Staphylococcus to trimethoprim-sulfamethoxazole, penicillin, spectinomycin and polymyxin B were over60%, and the highest resistance rate to penicillin was84.9%. High sensitivity drugs for clinical treatment were vancomycin, fosfomycin, nitrofurantoin, clarithromycin and minocycline. The results indicated that Staphylococcus drug resistant spectrum was widespread, and should be paid more attention. These provide theoretical basis for clinical prevention and treatment.Part3:Analysis of partial drug resistance genes of Staphylococcus from bovine mastitisThe genes of resistance gene (blaZ, ermC, tetK, tetL, tetM, tetO) related with β-lactam antibiotics, erythromycin and tetracycline were amplified by PCR. Primers were designed referenced to the relevant literature and Genbank sequence. Resistance genes blaZ, rmC, tetK, tetL, tetM were amplified and the sequence homology of these genes are up more than99%with Genbank reference. The results of resistance gene in383strains of staphylococcal caused bovine mastitis showed that the detective rate of genes blaZ was high and26.1%, and the detective rate of ermC, tetK, tetL, tetM were1.6%,14.1%,1.0%and1.3%, respectively. However, gene tetO was not detected. The analysis results of drug resistance gene test and drug resistant showed the drug resistance gene detection rate is lower than the rate of its related drugs, and the reasons for these antibiotic resistance mechanisms may be the existence of other resistance genes contributing for resistance mechanisms. The results indicated that Staphylococcus resistance mechanisms was complex, and its may be a major factor of bovine mastitis prevention and control difficult.