Active surveillance cultures and cohorting for carbapenem-resistant Acinetobacter baumannii in an endemic setting: an...

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a major challenge, yet the role of hospital-wide active surveillance cultures (ASC) outside outbreak settings remains debated. We assessed the impact of targeted ASC and cohorting integrated with an established infection prevention and control (IPC) program in an endemic setting on CRAB epidemiology.

A retrospective study was conducted at a 515-bed university hospital in Israel (January 2016-August 2025; 2020-2021 excluded). Screening of high-risk patients commenced in January 2023 utilizing four-limb skin sponges, with comprehensive implementation and patient cohorting initiated in July 2023. Outcomes were CRAB present on admission (POA) and hospital-acquired CRAB (overall and clinical subsets). We fit quasi-Poisson ITS models (January 2022-August 2025) with log link and exposure offsets (admissions for POA; hospital days for acquired); total counts were modeled with negative binomial regression. Cases averted were estimated with rate-based and ITS counterfactuals.

POA detection increased markedly after screening implementation (median 0.72 to 2.98 per 1,000 admissions), revealing a large reservoir of admission carriage. Overall hospital-acquired CRAB rates showed no sustained decline. In contrast, hospital-acquired clinical-CRAB fell substantially after July 2023 (mean 3.93 to 0.97 per 10,000 hospital-days), with a marked post-intervention level reduction in the ITS model (Incidence-rate ratio (IRR) 0.224, 95% CI 0.071-0.072, P = .0103). Counterfactual analyses estimated approximately 60-70 hospital-acquired clinical CRAB cases averted during follow-up.

In an endemic setting, hospital-wide ASC targeting high-risk patients unmasked extensive admission carriage and, combined with cohorting and other IPC measures, was associated with a substantial reduction in acquired clinical-CRAB cases.