Antimicrobial Resistance And Molecular Epidemiology Of OS-MRSA In Hulunbuir,inner Mongolia

Objective:To study the incidence and molecular epidemiological characteristics of OS-MRSA in Hulunbuir,Inner Mongolia.To investigate the possibility of direct identification of OS-MRSA by MALDI-TOF MS in clinical laboratory.Methods:Staphylococcus aureus was identified in the clinical laboratory of the General Hospital of Inner Mongolia Forestry during the 12 menstrual period of-2020in January 2015 in the General Hospital of Hulun Buir and other four hospitals in Hulun Buir.The MRSA and MSSA were screened according to the results of drug sensitivity test by using VITEK2-Compact automatic bacterial identification apparatus.The mec A gene was detected by agarose gel electrophoresis and OS-MRSA strain was screened out.MLST and spa typing of os-mrsa strains;Fifty strains of MRSA and MSSA were randomly selected for spa typing;Using the Ruo mode of MALDI-TOF MS mass spectrometer,the protein fingerprints of the screened os-mrsa and randomly selected MRSA and MSSA strains were analyzed to find the characteristic peaks.Statistical software SPSS 22.0 was used for analysis,and the utilization rate and composition ratio of counting data were described.X~2test was used for analysis and comparison,and P<0.05 was statistically significant.Result:(1)After mec A gene detection,13 strains of OS-MRSA were screened out,and the detection rate of OS-MRSA in Hulunbuir Area of Inner Mongolia was1.11%.(2)The sensitivity of OS-MRSA to Tegacyclin,Moxifloxacin,Linezolid,Oxacillin,Cefoxitin,Rifampicin,Penicillin G and Vancomycin was 100%,and it had different degrees of resistance to Eythromycin,Cotrimoxazole,Gentamicin,Clindamycin,Tetracycline,Ciprofloxacin and Levofloxacin..(3)10 types were obtained by spa typing and 8 types were obtained by MLST typing of OS-MRSA strains;A total of 15 different types were obtained by spa typing of MRSA strains.(4)Protein fingerprints were analyzed in the range of m/z 2000-5000,and the characteristic peak m/z3007 was statistically significant.Conclusion:(1)Comparing the results of this study with relevant literature,it was found that the incidence of OS-MRSA in Hulunbuir was lower than that in the whole country.(2)No resistance to Tigecycline,Moxifloxacin,Linezolid,Oxacillin,Vancomycin and Cefoxitin was found in OS-MRSA resistance experiments.Compared with the national MRSA drug sensitivity experiment in 2020,the drug resistance rate of Rifampicin,Gentamicin,Clindamycin and Levofloxacin was lower than the national drug resistance rate,and the drug resistance rate of Erythromycin was similar to the national MRSA drug resistance rate.The drug resistance rate of Cotrimoxazole was higher than that of MRSA in China.(3)No dominant type was found in OS-MRSA MLST and Spa genotypes,and the overall distribution was sporadic,MRSA Spa type t437 was the main epidemic type.(4)The MALDI-TOF MS mass spectrometer was used to identify the unique protein fingerprints of MRSA,MSSA and OS-MRSA,and could not directly identify MRSA,MSSA and OS-MRSA.