Screening Of Multi-resistant S.Aureus And Clearance Mechanism In Vivo

Staphylococcus aureus (S.aureus) is the main pathogens of mastitis, the major therapy method of mastitis in clinical was antibiotics, the abuse of antibiotics were not standardized, resulting in the generation of a large number of drug-resistant. So, study of S.aureus resistant spectrum, resistance genes and the clearance mechanism of pathogens are very important to guidance the treatment of mastitis (which was caused by S.aureus), and clinical rational use drug as well.Six new antibiotics were selected in this study, the resistant spectrum of121strains S.aureus about them were analysised. First, S.aureus were coated on blood agar plates, and six kinds of antibiotic susceptibility piece were affixed on plates evently, after cultivation at37℃for12h, then the diameter of each zone of inhibition were determined, the result according to version M100-S20of NCCLS in2010. In121strains S.aureus, MRSA were26strains and MSSA were93strains; intermediary were2strains in the result. The tolerance of S.aureus to six kinds disinfectants were detected by MIC. In this study, the tolerance strains of glutaraldehyde, dilute povidone-iodine, benzyl chloride, dichloro sodium cyanurate,84disinfectant and iodophor were95strains,65strains,65strains,10strains,3strains and0strain respectively. The resistance genes of S.aureus were detected by PCR, the mecA gene of MSSA, MRSA and intermediary were0strain,6strains and1strain, respectively; there were11strains S.aureus carrying qacA/B gene. We can get the conclusion from above experiment, MSSA maintained a good sensitivity to most antibiotics while MRSA performance for multi-drug resistant. S.aureus had a stronger tolerance to glutaraldehyde, dilute povidone-iodine and benzyl chloride. The bactericidal rate of dichloro sodium cyanurate,84disinfectant and iodophor to S.aureus reached more than90%, there was a certain correlation between the resistance and resistance gene of S.aureus.Bovine peripheral blood aseptically was collected, and lymphocytes were isolated, then total RNA were extracted from lymphocytes, after this cDNA was got by RT-PCR. Special primers of BoIFN-y were designed according to its gene sequences, then BoIFN-y was got by PCR, prokaryotic expression vector were built, to express rBoIFN-γ by IPTG induced. The result of SDS-PAGE and western blot show that the rBoIFN-y was successfully expressed. The rBoIFN-γ was purified to intramuscular injection cows which cow SCC over1×106/mL and infected with S.aureus, the SCC, blood, and cytokine were detected of cows to observe rBoIFN-y to enhance the immune effect. The total number of WBC and SCC of experimental animals decreased inflammatory. WBC and SCC were rised in control group. The study demonstrates that the rBoIFN-y had a certain effect on clinical mastitis, it can reduce the WBC and SCC.