Risk factors for microbiologic failure in children with Enterobacter species bacteremia.

Background: Enterobacter species are an important cause of healthcare-associated bloodstream infections (BSI) in children. Up to 19% of adult patients with Enterobacter BSI have recurrence of infection resistant to third-generation cephalosporins (3GCs) while on therapy with a 3GC. Data are lacking regarding the incidence of and risk factors for recurrence of infection in children with Enterobacter BSI.

Methods: We conducted a retrospective case-control study of patients aged ≤21 years old admitted to Texas Children's Hospital from January 2012 through December 2018 with Enterobacter BSI. The primary outcome was microbiologic failure from 72 hours to 30 days after the initial BSI (cases). The secondary outcome was isolation of a 3GC non-susceptible Enterobacter sp. from a patient with an initial 3GC-susceptible isolate.

Results: Twelve patients (6.7%) had microbiologic failure compared to 167 controls without microbiologic failure. Of the 138 patients (77.1%) with an Enterobacter sp. isolate that was initially susceptible to 3GCs, 3 (2.2%) developed a subsequent infection with a non-susceptible isolate. Predictors of microbiologic failure were having an alternative primary site of infection besides bacteremia without a focus or an urinary tract infection (OR, 9.64; 95% CI, 1.77-52.31; P < 0.01) and inadequate source control (OR, 22.16; 95% CI, 5.26-93.36; P < 0.001).

Conclusions: Source of infection and adequacy of source control are important considerations in preventing microbiologic failure. In-vitro susceptibilities can be used to select an antibiotic regimen for the treatment of Enterobacter BSI in children.