| Objective:1.The methicillin-resistant Staphylococcus aureus of skin and soft tissue infections(SSTIs)in third-class a hospitals in Jiangxi were collected to analyze the drug resistance rate of them to fusidic acid.2.To investigate the resistance mechanism of methicillin-resistant Staphylococcus aureus(MRSA)to fusidic acid in Jiangxi.Methods:A total of 60 strains of methicillin-resistant Staphylococcus aureus were collected from all patients with suppurative skin and soft tissue infection in outpatients and wards of prefecture-level Grade A hospitals in Jiangxi from December2017 to December 2018.The strain of fusidic acid was screened and the minimum inhibitory concentration(MIC)was determined according to the microbroth dilution method of the Clinical and Laboratory Standards Institute(CLSI).Resistant genes Fus B,Fus C,Fus D and Staphylococcus aureus A protein gene(spa gene)were detected by PCR method,and mutations of Fus B,Fus C and Fus D-negative resistant strains were detected by sequencing method.Results:Among the 60 MRSA strains collected,9 strains were screened out to be resistant to fucidic acid,with a resistance rate of 15%,of which 5 strains were resistant at low concentration(2ug/ml)and 4 strains were resistant at high concentration(> 128ug/ml).Fus B gene was detected in all the 5 strains with low concentration resistance,but not in the 4 strains with high concentration resistance.Fus A gene appeared in 4 strains with high concentration,all of which were substituted by L461 K amino acid.Fus C and Fus D genes were not found in 9 strains of MRSA.Conclusion:1.The drug resistance rate of MRSA to fusidic acid in Jiangxi was low,about15%;2.The mutation of drug-resistant genes was relatively simple.The strains with low concentration of drug resistance mainly expressed the Fus B gene,while the strains with high concentration of drug resistance all showed the mutation of Fus A gene,and the expressions of Fus C and Fus D genes were not found in the 9 strains with drug resistance. |
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