Assessing antibiotic utilization trends and outcomes in patients with carbapenem-resistant Acinetobacter baumannii (CRAB) infections.

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii (CRAB) remains an urgent public health threat due to challenges with resistance and treatment. This study evaluated antibiotic utilization trends and outcomes in the treatment of CRAB infections in the Department of Veteran Affairs (VA) patient population.

METHODS

This national retrospective cohort study included veterans with at least one positive culture for CRAB between January 2018 to December 2023. Data from national VA registries, along with chart reviews, were analyzed for demographics, microbial cultures, antimicrobial treatment(s), and mortality. Descriptive statistics and logistic regression, accounting for clustering within patients, were used.

RESULTS

Among 717 unique patients with 946 monomicrobial and polymicrobial CRAB cultures of 717 unique patients across 75 VA facilities, 352 monomicrobial cultures of 302 unique patients were identified. Ampicillin-sulbactam, tetracycline, and cephalosporin use increased over time (P < .002, P < .001, P = .005), whereas polymyxin use decreased over time (P = .009). CRAB isolates were most frequently susceptible to aminoglycosides. Adjusted analyses revealed higher 30- and 90-day mortality rates in patients that received combination versus monotherapy; OR 2.97, CI (1.35-6.51), OR 2.75, CI (1.29-5.84).

CONCLUSIONS

Antimicrobial use for CRAB infections changed as updated guidelines were adopted. Mortality rates were highest among patients receiving combination therapy, likely reflecting greater severity of illness.