Carbapenem-resistant Acinetobacter baumannii complex in the United States-An epidemiological and molecular...

Understanding the epidemiology of carbapenem-resistant A. baumannii complex (CRAB) and the patients impacted is an important step toward informing better infection prevention and control practices and improving public health response.

Active, population-based surveillance was conducted for CRAB in 9 U.S. sites from January 1 to December 31, 2019. Medical records were reviewed, isolates were collected and characterized including antimicrobial susceptibility testing and whole genome sequencing.

Among 136 incident cases in 2019, 66 isolates were collected and characterized; 56.5% were from cases who were male, 54.5% were from persons of Black or African American race with non-Hispanic ethnicity, and the median age was 63.5 years. Most isolates, 77.2%, were isolated from urine, and 50.0% were collected in the outpatient setting; 72.7% of isolates harbored an acquired carbapenemase gene (aCP), predominantly bla_OXA-23 or bla_OXA-24/40; however, an isolate with bla_NDM was identified. The antimicrobial agent with the most in vitro activity was cefiderocol (96.9% of isolates were susceptible).

Our surveillance found that CRAB isolates in the U.S. commonly harbor an aCP, have an antimicrobial susceptibility profile that is defined as difficult-to-treat resistance, and epidemiologically are similar regardless of the presence of an aCP.