Objective This study aimed to investigate the drug resistance and distribution of resistant genes in clinical isolates of Staphylococcus aureus (SA) in the Yangzhou region. The laboratory findings provide valuable insights for the diagnosis, treatment, and scientific prevention of clindamycin-resistant SA infections in the local area.
Methods Clinical samples of SA were collected from some tertiary hospitals in this region from 2016 to 2022. Broth microdilution method was used to detect the drug resistance phenotype of SA. MLST types were determined after whole genome sequencing analysis, and drug resistance genes were screened in the CARD database.
Results A total of 200 clinical SA isolates were collected, and 86 SA were confirmed to be clindamycin resistant, of which 43 (43/86, 50%) were induced drug resistance (iMLSB). The clindamycin-resistant SA strains exhibited diverse resistance patterns, with 15 different phenotypes observed for cMLSB and 13 phenotypes for iMLSB. Among these, 4 strains were resistant to more than six different drugs in the cMLSB group, and 7 strains were resistant to more than six drugs in the iMLSB group. Analysis of 17 resistant genes belonging to nine classes revealed that 10 strains (11.63%) carried six or more resistant genes, with a higher prevalence of iMLSB (9.30%, 8/86) compared to cMLSB (2.33%, 2/86). The 86 SA strains were classified into 12 different clonal complexes (CC), with CC398 (27.90%) and CC5 (15.12%) being the dominant types.
Conclusion Compared to cMLSB, iMLSB strains of SA exhibited higher drug resistance and a greater prevalence of resistant genes. The CC5 clonal complex, with an average of 7.31 carried resistant genes, was predominantly associated with iMLSB (84.62%, 11/13). The drug resistance profile and resistant gene characteristics of iMLSB SA in the local area deserve attention. The evolution pattern of CC5-ermA-SA appears unique and may confer increased tolerance to antibiotics.
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