Study: Clinical Burden of Acinetobacter baumannii in U.S. Hospitals

An April 17 retrospective cohort study published in the journal BMC Infectious Diseases entitled, “Clinical burden of Acinetobacter baumannii, including carbapenem-resistant A. baumannii, in hospitalized adult patients in the USA between 2018 and 2022” aimed to address the limited epidemiological data available on Acinetobacter baumannii and carbapenem-resistant A. baumannii (CRAB) in U.S. hospitals. Researchers analyzed microbiology data from the PINC AI Database, covering hospitalized patients across the U.S. from January 1, 2018, to December 31, 2022. The goal was to determine the incidence rates of A. baumannii and CRAB at both hospitalization and individual patient levels, as well as to assess patient characteristics, comorbidities, and clinical outcomes associated with these infections.

Over the five-year period, the study identified 7,270 hospital encounters involving at least one clinical culture positive for A. baumannii. The overall incidence was 1.19 cases per 100 hospitalization encounters and 1.33 per 100 unique patients. CRAB was identified in 2,708 of these encounters, corresponding to an incidence of 0.44 cases per 100 hospitalizations. The highest incidence rates for CRAB were concentrated in the central regions of the U.S., particularly the West South Central (0.78), East North Central (0.67), and East South Central (0.63) regions.

Patients with CRAB had significantly more A. baumannii-positive cultures (20.9%) compared to those with carbapenem-susceptible A. baumannii (CSAB) at 10.0%. Additionally, CRAB patients had a higher prevalence of co-infection with other Gram-negative bacteria within ±3 days of their initial A. baumannii culture (47.2% vs. 42.9%). Importantly, in-hospital mortality was markedly higher in patients with CRAB (20.5%) compared to those with CSAB (11.3%), indicating a more severe disease burden associated with resistant strains.

In conclusion, A. baumannii was found in approximately 1% of adult hospitalizations across the U.S. in this multicenter study. Over one-third of these cases involved CRAB, which showed regional variation, with the most central areas of the country experiencing the highest rates. The findings underscore the need for heightened clinical awareness and targeted infection control strategies, especially in regions with increasing A. baumannii and CRAB prevalence.