Study On Disinfectant Resistance Of Common Bacteria In Pig Farms And Intracellular Kinetics Of Staphylococcus Aureus Under Antibiotic Stress

In order to explore the sensitivity and resistance of common bacteria in pig farms to disinfectants and the survival mechanism of S.aureus under antibiotic pressure,suspension quantitative germicidal test was used to evaluate the germicidal efficacy of imported potassium bisulfate complex(A),domestic potassium bisulfate complex(B)and domestic glutaraldehyde-decamethyl ammonium bromide(C)against four bacteria(E.coli,Salmonella,Streptococcus and S.aureus).Four bacteria were continuously passaged under disinfectant pressure to evaluate their resistance by testing MBC and MIC of each generation.The intracellular and extracellular viable counts of S.aureus and PAM were counted at different time points,and the m RNA expressions of 15 genes closely related to the survival of S.aureus were detected by q RT-PCR.The results showed that at 4°C,25°C and 37°C,disinfectant A(1:200)and disinfectant B(1:400)could completely kill the four bacteria within 1–5 min;Disinfectant C can basically kill four bacteria within 15-30 min.In the evaluation of bacterial resistance to disinfectants,it was found that the MBC of the three disinfectants was 0.5–16times that of the first generation.In the intracellular survival test of S.aureus,the viable count of S.aureus was 1.03×10~4CFU/m L at 3 h and 1.59×10~5CFU/m L at 13 h.q RT-PCR results s howed that 5 genes were up-regulated and 10 genes were down-regulated after 3 h of internalization,that 3 genes were up-regulated and 12 genes were down-regulated after 13.According to the relevant literature,three genes arg A,Hla and sod A are related to the survival mechanism of S.aureus.Conclusion:Three disinfectants have good killing effect on four kinds of bacteria at the recommended concentration.After continuous passage,E.coli and Salmonella s howed no resistance to potassium persulfate complex,while Streptococcus and S.aureus showed varying degrees of resistance to disinfectants.S.aureus can invade porcine alveolar macrophages and persist.