Controlling Imipenem-Resistant Pseudomonas aeruginosa in Hospitals: Effect of Improved Infection Control Measures from an Interrupted Time-Series Study

Imipenem-resistant Pseudomonas aeruginosa (IRPA) causes serious healthcare-associated infections and negatively affects clinical outcomes. This study aims to determine if a structured bundle of enhanced infection-control measures can effectively reduce hospital-acquired IRPA cases at a tertiary care hospital. A retrospective interrupted time series analysis was conducted over two consecutive twelve-month periods: (1) 2023 served as the baseline period; (2) 2024 as the enhanced intervention period. The interventions included weekly active surveillance, prompt notification to physicians after positive culture results, structured on-site audits with a standardized checklist for isolating multidrug-resistant organisms, and monthly departmental performance reports. A total of 850 clinical isolates were analyzed. The main outcomes measured were the overall IRPA incidence, hospital-acquired IRPA infection rates, adherence to contact precautions for IRPA patients, and total Imipenem use, each expressed as a rate per 1,000 patient-days. Segmented linear regression was used for the interrupted time series analysis. IRPA incidence decreased from 1.842 to 0.963 cases per 1,000 patient-days (p < 0.001), and hospital-acquired IRPA infection rates dropped from 0.214 to 0.088 per 1,000 patient-days (p = 0.001). Contact isolation compliance increased from 31.4% to 76.2% (p < 0.001). Imipenem use rose to 1.183 defined daily doses per 1,000 patient-days per quarter (p = 0.002), with no significant change in this trend due to the intervention (p = 0.112). The implementation of a structured infection control bundle focusing on weekly surveillance and real-time notification led to a significant clinical and statistical reduction in hospital-acquired IRPA, despite increased Imipenem use. These findings offer practical evidence for resource-limited tertiary care settings.