A. baumannii-positive cultures linked to infection in ICU patients
The presence of carbapenem-resistant Acinetobacter baumannii on surveillance cultures were strongly correlated with the onset of carbapenem-resistant A. baumannii infections in trauma patients, recent data suggest.
In a retrospective cohort study, researchers evaluated 364 consecutive patients seen at the trauma ICU of a tertiary hospital between January 2010 and November 2011. Surveillance cultures were performed at admission to rule out carbapenem-resistant gram-negative bacilli, and the tests were continued weekly for the duration of the patients’ stays.
The researchers found carbapenem-resistant A. baumannii on 49 (13.5%) of the surveillance cultures. Moreover, patients with positive surveillance cultures had an 8.4 (95% CI, 5.6-12.7) times greater risk for subsequent A. baumannii infection vs. those with negative cultures. In multivariable analysis, the researchers found a greater likelihood of clinical infection associated with positive surveillance cultures (RR=5.9; 95% CI, 3.8-9.3) and mechanical ventilation (RR=4.3; 95% CI, 1.03-18.2). Survival analysis found positive surveillance culture to be the only variable associated with clinical infection onset (HR=16.3; 95% CI, 9.1-29.1). Notably, patients with A. baumannii pathogens on surveillance cultures during their ICU stays had a 15.5 times greater likelihood of developing a carbapenem-resistant A. baumannii infection.
According to the researchers, these findings underscore the value of surveillance cultures for ICU patients, particularly in cases of nosocomial colonization.
“Surveillance cultures upon admission to ICUs are a valuable infection control tool that should not only be used for cohorting patients but also as a signature marker for subsequent clinical infections,” the researchers wrote. “We now know that we should target not only prevention of acquisition of carbapenem-resistant A. baumannii … but also focus our efforts on patients that are known to be colonized.”
Disclosure: The researchers report no relevant financial disclosures.