Trends in Pseudomonas aeruginosa Resistance After a Four-Dimensional Antimicrobial Stewardship Intervention

This single-center retrospective study analyzed de-duplicated Pseudomonas aeruginosa isolates collected at Huaian Municipal Infectious Diseases Hospital from 2023 to 2025. A total of 121 unique isolates were included, of which 83.5% were from sputum. Antimicrobial susceptibility testing (AST) was performed using an automated microbiology system, and minimum inhibitory concentration (MIC) results were interpreted according to CLSI M100, 33rd edition. In early 2024, a four-dimensional linkage-targeted antimicrobial stewardship intervention was implemented in the Respiratory and Tuberculosis Department (Resp-TB) (n = 97), comprising: (1) dynamic antimicrobial resistance surveillance with quarterly feedback; (2) risk-stratified antimicrobial prescribing based on local susceptibility data; (3) standardized specimen collection protocols; and (4) enhanced infection prevention and control measures. In the Resp-TB, the overall resistance rates were 74.19% in 2023, 81.63% in 2024, and 82.93% in 2025, with no significant reduction after the intervention (p ≈ 0.37). By 2025, resistance to tobramycin was 0/41 (0.00%), cefepime was 1/41 (2.44%), and piperacillin-tazobactam was 0/41 (0.00%); levofloxacin resistance reached 15/41 (36.59%). Trimethoprim-sulfamethoxazole resistance remained high across the study period. These findings show persistent antimicrobial resistance in the Resp-TB after implementation of the intervention, while resistance to selected agents, including tobramycin, cefepime, and piperacillin-tazobactam, remained low in 2025.