Abstract
OBJECTIVE: To evaluate microbial distribution and antimicrobial resistance (AMR) patterns in clinical isolates from 13 tertiary hospitals and one secondary hospital in Tianjin (2021-2023) to inform precision-driven antimicrobial stewardship and infection control interventions. METHODS: In this retrospective, multicenter study, we collected routine diagnostic specimens-including sputum, fecal samples, secretions, blood, and drainage fluids. Data were processed per standardized protocols (CARSS, CHINET) and interpreted using current CLSI-M100 breakpoints. Statistical analyses were performed with SPSS 20.0 (significance set at two-tailed P < 0.05). RESULTS: Sputum specimens increased from 39.1% to 43.0%, while urine samples and secretions declined. Klebsiella pneumoniae prevalence rose from 18.3% to 20.3%, whereas Escherichia coli remained stable. E. coli maintained excellent susceptibility to carbapenems and amikacin (≤2% resistance); notably, ceftazidime/avibactam resistance declined from 7.2% to 3.4% (P = 0.005) amid a significant increase in cefepime resistance (24.4% to 29.6%, P < 0.001). K. pneumoniae exhibited parallel trends, with escalating resistance to β-lactam/β-lactamase inhibitor agents. In Pseudomonas aeruginosa, aminoglycoside, and carbapenem profiles remained stable, while ceftazidime/avibactam sensitivity markedly improved, suggesting shifts in underlying resistance mechanisms. Acinetobacter baumannii showed enhanced susceptibility to aminoglycosides, β-lactam inhibitors, and fluoroquinolones; however, carbapenem-resistant isolates continued to exhibit near-universal resistance. Among gram-positive pathogens, methicillin-resistant Staphylococcus aureus sustained near-universal β-lactam resistance with improved rifampicin sensitivity, while glycopeptides and linezolid remained fully active. Enterococcus faecalis demonstrated reduced ampicillin resistance, contrasting with E. faecium's near-pan-resistance to β-lactams and fluoroquinolones. CONCLUSION: Evolving, species-specific AMR patterns in Tianjin hospitals highlight the urgent need for real-time, regionally stratified surveillance and molecularly informed stewardship strategies to guide targeted antimicrobial interventions and improve clinical outcomes.