Epidemiology and treatment of carbapenemase-producing Enterobacteriaceae bacteremia in a community hospital setting

Background: Carbapenemase-producing Enterobacteriaceae (CPE) infections are a rapidly evolving global threat. With bacteremia mortality rates exceeding 40%, limited consensus exists regarding optimal antimicrobial treatment. Objectives: To characterize our institution’s CPE bacteremia population and describe the antimicrobial regimens used for treatment. Methods: A dual-centre retrospective chart review was conducted of adult CPE bacteremia patients admitted between January 1, 2010 and April 30, 2017. Baseline demographics included out-of-country hospitalization, causative organism, and susceptibilities. Treatment details included antimicrobial agent, dosing regimen, and use of monotherapy or combination therapy. Clinical outcomes included 30-day all-cause mortality and 30-day re-admission rates. Results: Thirteen cases of CPE bacteremia were reviewed. Nine patients had previously been hospitalized in the Indian subcontinent. Twelve isolates produced the New Delhi metallo-beta-lactamase-1 (NDM-1). All isolates were sensitive (n = 8) or intermediate (n = 5) to tigecycline. An equal number of cases were treated with monotherapy (n = 6) and combination therapy (n = 6). The most commonly prescribed antimicrobials were colistin (n = 7) and tigecycline (n = 8). The overall 30-day mortality and re-admission rates were 54% (7/13) and 50% (3/6), respectively, although the effect of potential confounders such as causative CPE, monomicrobial or polymicrobial infection, or delay in therapy were not considered. Conclusions: This study highlights the largest Canadian CPE bacteremia cohort to date. CPE bacteremia most commonly occurred in patients with prior hospitalization in the Indian subcontinent. Based on our antimicrobial susceptibility testing results, tigecycline may have a role as part of empiric therapy at our institution.