Dissemination and Molecular Characterization of Staphylococcus aureus at a Tertiary Referral Hospital in Xiamen City, China

Abstract

Staphylococcus aureus is a global epidemic pathogen that causes heavy disease burden. The aim of this study was to determine which globally known S. aureus lineages are currently present in a hospital of Xiamen. Therefore, the 426 S. aureus strains were detected by Melting Curve Analysis (MCA) and genotyped by Pulsed Field Gel Electrophoresis (PFGE) as well as Multicolor Melting Curve Analysis-Based Multilocus Melt Typing (MLMT). In addition, Multilocus Sequence Typing (MLST) was used to identify 108 representative strains. In light of eighteen antibiotics except for Vancomycin (by Broth Dilution Method), we used the Kirby-Bauer disc diffusion method to assess antibiotic susceptibility of 426 S. aureus strains. Finally, PFGE analysis revealed 14 different patterns with three major patterns (C10, C8, and C11) that accounted for 69.42% of all S. aureus strains, and MT-1~MT-5 occupied most part of the strains by MLMT. MLST revealed 25 different STs with the predominant types being ST239, ST59, and ST188. There have been 8 antibiotics that showed more than 50% resistance of all S. aureus strains. In summary, we found several of the lineages are predominant in our hospital. And antibiotic resistance is still a severe problem that needs to be controlled in clinic.

Figure 1

The PFGE cluster analysis of 108 representative S. aureus strains.

Figure 2

MLMT analysis results of 426 S. aureus strains with PFGE. The number-frequency (%) of each MT is given together with the number of the corresponding PFGE clusters and the type and number of PFGE clusters of all the MTs obtained from the 426 strains. The size of the pies illustrates the relative number of MTs but not in a true scale.

Figure 3

MST of 108 representative strains by MLST. MST: minimum spanning tree.