Study of molecular characteristics of methicillin-resistant Staphylococcus aureus in Maanshan area

Abstract

To identity the distribution of enterotoxin and hemolysin, as well as the clonal complexes and drug resistance of the strains of methicillin-resistant Staphylococcus aureus (MRSA) in Maanshan region. Automatic enzyme-linked fluorescent assay system and PCR technology were used to identify the distribution of enterotoxin and hemolysin genes. Seven Staphylococcus aureus hourskeeping genes were choosed as the target genes for multilocus sequence typing (MLST) on 34 strains of MRSA and 3 strains of methicillin-sensitive Staphylococcus aureus (MSSA), comparing the data with the online database and obtaining the sequence typing (ST), conducting affinity analysis on its ST based on eBURST, testing in agar dilution method the drug resistance of MRSA against 12 antibiotics. 50.9% of the 210 Staphylococcus aureus strains were enterotoxin positive, and 97.1% of them carried hemolysin genes as all 51 strains of MRSA carried hemolsin genes. The 34 MRSA strains were divided into 10 STs, ranging in sequence ST239 (47.1%, 16/34), ST5 (17.6%, 6/34). Three MSSA strains belonged to ST188, ST1281 and ST7, respectively. Seventeen strains from the patients were divided into 6 STs, ranging in sequence ST239 (35.3%, 6/17) and ST5 (29.4%, 5/17). Twenty strains from food sources were divided into 9 STs, ranging in sequence ST239 (45.0%, 9/20) and ST7 (15.0%, 3/20). STs of ST585, ST630 and ST239 were close in affinity, while the rest were distant in affinity. Except for vancomycin, all the strains were found with drug resistance to varying extent to the 10 antibiotics tested. Existence of Staphylococcus aureus hemotoxin was universal; ST239 was the main predominant MRSA in Maanshan region, with distant affinity among the STs.