BackgroundCarbapenem-resistant Acinetobacter baumannii (CRAB) causes life-threating hospital-acquired infections in critically-ill patients. Due to a limited number of Intensive-Care-Unit (ICU) beds, these patients are often treated in high-dependency (HD) non-ICUs within internal-medicine wards (IMW) in Israel. We aimed to assess the effectiveness of a multi-layered infection-control intervention on CRAB infection-rate in IMWs, especially in its HD non-ICUs with ongoing CRAB transmission. MethodsA quasi-experimental, before-and-after, interrupted time-series study with control outcomes conducted from January 2019 through June 2022. We conducted a multi-layered intervention over 3.5 years which included 4 phases: 1) Pre-intervention; 2) Intervention-introduction: introduced enhanced environment cleaning; 3) Intervention phase 1: introduced active surveillance; 4) Intervention phase 2: introduced CRAB-positive patient cohorting, in addition to previous ongoing measures taken. ResultsCRAB was isolated from 204 patients aged 69.8y/o ± 15.86y, 59.8% male. CRAB-positive clinical samples were found in 34.3% of these patients. Mean hospital length-of-stay was 30.5 days, with a 30-day post-discharge mortality-rate of 55.9%. Mean CRAB clinical cases decreased from 0.89 in pre-intervention to 0.11 at the end of Phase 2, with a change in slope and level after the intervention of p= 0.02 (CI: -0.204- to -0.040) and p=0.004 (CI: -0.013 to -0.003), respectively. ConclusionsThis multi-layered intervention, including enhanced environment cleaning, active surveillance, and patient cohorting, successfully reduced CRAB acquisition in IMWs and their HD non-ICUs.