Tailoring Interventions for Control of Endemic Carbapenem-Resistant Acinetobacter baumannii: An Interrupted Time Series Analysis

Background: We examined temporal trends in carbapenem-resistant Acinetobacter baumannii (CRAB) infections in a hospital with hyperendemic CRAB and assessed the efficacy of varied infection control strategies in different ward types. Methods: We retrospectively analyzed all CRAB clinical samples from 2006 to 2019 and categorized infections as hospital-onset (HO) or community-onset. We used interrupted time series analysis to assess the impact of interventions on the incidence of all HO-CRAB infections and bloodstream infections (BSIs) at the hospital and ward group levels. Results: Over 14 years, 4009 CRAB infections were identified (89.7% HO), with 813 CRAB BSI (93.2% HO). The incidence per 100 000 patient-days of CRAB infections peaked in 2008 at 79.1, and that of CRAB BSI peaked in 2010 at 16.2. These rates decreased by two-thirds by 2019. In the general intensive care unit (ICU), hand hygiene and environmental cleaning interventions were followed by a significant reduction in the level of HO-CRAB infections, with an additional decrease in the slope after the introduction of active surveillance and 2% chlorhexidine bathing. In the surgical ICU and surgical department, a reduction in slope or level of CRAB infection was observed after moving ventilated patients to single rooms. In medical wards, a multimodal intervention was followed by a reduction in the slope of HO-CRAB infections and BSIs. In wards where CRAB infections were uncommon, the incidence of HO-CRAB infections decreased throughout the study period. Conclusions: Ward-specific variables determine the success of interventions in reducing CRAB infections; therefore, interventions should be tailored to each setting.