Antimicrobial Resistance Characteristics of Staphylococcus aureus Isolated From Both Tertiary Hospitals, One Western Medicine Hospital and One Traditional Chinese Medicine Hospital, in Shanghai, China From 2014-2023.

Purpose: Methicillin-resistant Staphylococcus aureus (MRSA) represents a growing threat to global public health. The aim of this study was to characterize the epidemiology and resistance of Staphylococcus aureus (S. aureus) collected between 2014 and 2023 from two Grade A tertiary hospitals in Shanghai: Shanghai Municipal Hospital of Traditional Chinese Medicine (STCMH), and Shanghai General Hospital (SGH).

Methods: A total of 9816 non-duplicate S. aureus isolates (STCMH: n=2714; SGH: n=7102) were retrospectively analyzed. Antimicrobial susceptibility testing was conducted following CLSI guidelines. Predictors of bacterial clearance in S. aureus-infected patients were identified using univariate and LASSO regression and incorporated into a nomogram model.

Results: S. aureus was primarily isolated from sputum and wound secretions, largely from the Intensive Care Medicine (ICU) and surgical departments, and most frequently affected patients aged ≥65 in both institutions. Compared to STCMH, SGH isolates exhibited higher resistance rates to penicillin G (91.00% vs 70.12%), levofloxacin (57.27% vs 49.48%), moxifloxacin (55.34% vs 46.54%), gentamicin (40.07% vs 36.77%), and rifampin (3.17% vs.1.58%). The MRSA prevalence declined markedly at STCMH, dropping from 67.70% in 2017 to 33.30% in 2023, but remained elevated at SGH (54.79% to 69.00%). Furthermore, MRSA isolates from SGH showed higher resistance to levofloxacin (80.75% vs 76.71%), but lower resistance to erythromycin (84.37%vs 87.68%) and moxifloxacin (65.03% vs 74.26%) compared to those from STCMH. After 2016, STCMH revealed accelerated declines in MRSA resistance to erythromycin, clindamycin, and rifampicin. Both hospitals maintained 100% susceptibility to vancomycin, linezolid, and quinupristin/dalfopristin. The nomogram (AUC=0.654) identified combined antibiotic-TCM therapy, leukocyte and lymphocyte counts, and C-reactive protein levels as independent predictors of bacterial clearance.

Conclusion: STCMH had lower MRSA prevalence and S. aureus resistance rates than SGH, and TCM-antibiotic combination therapy might promote bacterial clearance, suggesting TCM's potential in combating antimicrobial resistance, which needs further multicenter validation to support the implementation of antimicrobial stewardship strategies.