496. Carbapenem-resistant Enterobacter: A Case-Case–Control Investigation

BACKGROUND. BACKGROUND: The World Health Organization has declared carbapenem-resistant Enterobacteriaceae (CRE) as a worldwide public health threat. Analyzing the epidemiology of CRE was derived from cohorts consisting primarily of Klebsiella pneumoniae isolates. The second most frequent CRE is Enterobacter (CREn), but its molecular and clinical epidemiology differ from that of K. pneumoniae, and it has not been analyzed while implementing updated methodological tools and design. METHODS: A matched case-case–control investigation was conducted at Shamir (Assaf Harofeh) Medical Center, Israel, for calendar years 2007–2017. Each CREn case was matched to a carbapenem-susceptible Enterobacter (CSEn) case and to an uninfected control (1:1:1 ratio). Logistic and Cox regression-matched analyses were conducted in order to study predictors and outcomes of CREn colonization and/or infection, respectively. RESULTS: The study included 216 cases (72 in each group). Numerous predictors were significantly associated with CREn as per bivariable analyses, but the only independent significant predictors were: (1) recent (3 months) exposure to fluoroquinolones (aOR=2.94, P = 0.04), (2) intensive care unit stay in current hospitalization prior to culture (aOR=3.56, P = 0.003), and (3) a rapidly fatal McCabe score (aOR=0.471, P = 0.01). Patients with CREn suffered from significant delays in instituting appropriate antimicrobials (P = 0.03), and for those who survived the hospitalization, were more frequently discharged to a long-term care facility after being admitted to the index hospitalization from home (aOR=3.3, P = 0.02). CONCLUSION: This case-case–control-matched investigation of CREn epidemiology, revealed a unique modifiable predictor, i.e., recent fluoroquinolone exposure, which could represent a target for stewardship intervention. The case-case–control-matched design allowed for the control of numerous confounders previously reported to be associated with CREn but may represent a risk factor for Enterobacter infection in general. As with other CRE, CREn carriers suffer from significant delays in initiation of appropriate antimicrobials and from worse outcomes. DISCLOSURES: All authors: No reported disclosures.