Risk Factors Associated with Carbapenemase-Producing Carbapenem-Resistant Enterobacteriaceae Positive Cultures in a Cohort of US Veterans

Background: Carbapenem-resistant Enterobacteriaceae (CRE) cause approximately 13 100 infections, with an 8% mortality rate in the United States annually. Carbapenemase-producing CRE (CP-CRE) a subset of CRE infections infections have much higher mortality rates (40%-50%). There has been little research on characteristics unique to CP-CRE. The goal of the current study was to assess differences between US veterans with non-CP-CRE and those with CP-CRE cultures. Methods: A retrospective cohort of veterans with CRE cultures from 2013-2018 and their demographic, medical, and facility level covariates were collected. Clustered multiple logistic regression models were used to assess independent factors associated with CP-CRE. Results: The study included 3096 unique patients with cultures positive for either non-CP-CRE or CP-CRE. Being African American (odds ratio, 1.44 [95% confidence interval, 1.15-1.80]), diagnosis in 2017 (3.11 [2.13-4.54]) or 2018 (3.93 [2.64-5.84]), congestive heart failure (1.35 [1.11-1.64]), and gastroesophageal reflux disease (1.39 [1.03-1.87]) were associated with CP-CRE cultures. There was no known antibiotic exposure in the previous year for 752 patients (24.3% of the included patients). Those with no known antibiotic exposure had increased frequency of prolonged proton pump inhibitor use (17.3%) compared to those with known antibiotic exposure (5.6%). Discussion: Among a cohort of patients with CRE, African Americans, patients with congestive heart failure, and those with gastroesophageal reflux disease had greater odds of having a CP-CRE culture. Roughly 1 in 4 patients with CP-CRE had no known antibiotic exposure in the year before their positive culture.