717Clinical characteristics and outcome of metallo-β-lactamase-producing Enterobacter cloacae bacteremia at a tertiary care cancer center in Japan

Background. Recent reports suggest that metallo-β-lactamase (MBL)-producing Enterobacter cloacae increases as a pathogen of healthcare-associated infections in Japan. Bacteremia caused by MBL-producing E. cloacae is a major concern due to the resistance to most β-lactams including carbapenems. However, little is known about MBL-producing E. cloacae bacteremia in patients with cancer. The aim of this study is to examine the clinical characteristics, outcome, and risk factors of MBL-producing E. cloacae bacteremia. Methods. A retrospective cohort study in patients with E. cloacae bacteremia was conducted at an 800-bed tertiary-care cancer center in Japan, from April 2011 through March 2014. Isolates demonstrating intermediate or resistant to third generation cephalosporins or carbapenems were screened and confirmed. We reviewed demographics, comorbidities, and other clinical characteristics. Mortality and risk factors of MBLproducing E. cloacae bacteremia were also assessed. Results. During the study period, 44 cases were diagnosed with E. cloacae bacteremia. The incidence of healthcare-facility onset E. cloacae bacteremia was 0.57 per 10,000 patient-days. MBL-producing E. cloacae were detected in 11 cases (25%). After screening of MBL-producing strains, PCR analyses were carried out for 5 of 11 isolates, all of which were IMP-1 type beta-lactamase. Among bacteremic patients with MBL-producing E. cloacae, inappropriate empirical antimicrobial therapies were likely to be selected compared to those with MBL-non-producing E. cloacae (90.9% vs 54.5%, P = 0.067). However, 30-day all-cause mortality between two groups was not different (9.1% vs 12.1%, P = 1.0). Factors associated with the development of MBL-producing E. cloacae bacteremia were prior antimicrobial use (adjusted odds ratio [aOR], 9.25; 95% confidence interval [CI], 1.27-67.4; P = 0.028) and no history of recent surgery (aOR, 13.8; 95% CI, 1.16-164; P = 0.033). Conclusion. The frequency of MBL-producing E. cloacae bacteremia was high among E. cloacae bacteremia. Prior antimicrobial use and no history of recent surgery were associated with MBL-producing E. cloacae bacteremia. Mortality was not different regardless of antimicrobial therapies and type of resistance. Disclosures. All authors: No reported disclosures.