Retrospective cohort study examines MRSA prevalence and resistance patterns in nosocomial bloodstream infections among 96 patients in central China.

This retrospective cohort study evaluated the antimicrobial resistance prevalence and genomic epidemiology of Staphylococcus aureus in patients with nosocomial bloodstream infections at a tertiary hospital in central China. The analysis included 96 isolates, examining susceptibility to linezolid, rifampicin, vancomycin, tigecycline, and methicillin, alongside genomic characteristics such as multilocus sequence typing and virulence factors.

Regarding antimicrobial susceptibility, all 96 strains (96/96) demonstrated susceptibility to linezolid and rifampicin. However, one vancomycin-resistant strain (1/96) and one tigecycline-resistant strain (1/96) were identified. Additionally, one phenotypically discordant MRSA strain (1/96) was detected. The overall proportion of MRSA remained stable, ranging from 57.14% to 100.00% (70/96 isolates), while the total number of S. aureus isolates showed a downward trend. Infection rates varied by department, with the Department of Nephrology reporting the highest rate at 36.46%.

Genomic analysis revealed 29 resistance gene types and an average of 74 virulence genes per strain, with 45 core virulence genes identified. Multilocus sequence typing identified 21 sequence types, with ST59 being dominant (21.88%) and ST22 persistently epidemic. SCCmec type IV was predominant (58.93%), and three pseudo-SCCmec carriers were detected. No adverse events, serious adverse events, or discontinuations were reported.

The study provides reliable evidence for precise medication selection and targeted prevention of MRSA bloodstream infections, offering references for understanding S. aureus antimicrobial resistance evolution. However, the study design is observational, and specific p-values or confidence intervals were not reported for most outcomes. Consequently, these findings should be interpreted as descriptive data rather than definitive proof of causality or efficacy in broader clinical contexts.