788. Enterobacter cloacae Infection Characteristics and Outcomes in Military Personnel who Sustained Trauma in Iraq and Afghanistan

Abstract

Background Enterobacter cloacae is a Gram-negative rod with chromosomally-induced Amp-C β-lactamase with multidrug-resistant potential. Joint Trauma System guidelines for treating combat wounds include prophylaxis with cefazolin and ertapenem, potent inducers of Amp-C. We evaluated clinical characteristics, antibiotic utilization, and outcomes associated with battlefield-related E. cloacae infections. MethodsAll initial solitary (those with single isolates) and serial E. cloacae isolates (≥24 hours from initial isolate from any site) were collected from the Trauma Infectious Disease Outcomes Study (6/2009-12/2014). Inclusion required E. cloacae isolation from a clinical infection. Amp-C-inducing β-lactams were classified based on induction potential and lability to the Amp-C β-lactamase as Amp-C induction levels. ResultsOf 653 E. cloacae isolates, 253 met inclusion criteria – 64 patients had only initial isolates, 54 patients had serial isolates. Patients were largely male (99%), median age 23 years (IQR 21-27), with injury severity score of 34 (IQR 24-45). Initial isolates were wound (70%), respiratory (22%), blood (7%), urine (1%), and other (1%). Patients commonly had blast injuries (89%), required ICU admission (95%), and had a median hospital stay of 57 days (IQR 39-82). Patients with serial isolates showed a trend towards earlier clinical infection (5 vs 8 days, P = 0.07). They were also less likely to receive carbapenems prior to E. cloacae isolation compared to those with only initial isolates (4% vs 38%) and more likely to receive 1st generation cephalosporins (79% vs 58%, P = 0.01). The serial isolate group received more days of 1st generation cephalosporins (median 6 days vs 2.5 days, P = 0.01). Cumulative antimicrobial therapy trended towards significance and was greater with the serial isolates (median 100 days vs 74 days, P = 0.08). There was no difference in number of surgical interventions between those with and without serial isolates (P = 0.54). Overall, 6 patients died. Conclusion E. cloacae infections after battlefield trauma were frequently encountered and associated with exposure to 1st generation cephalosporins. Serial infections did not correlate to worse patient outcomes but displayed a trend towards an overall greater duration of antibiotic use.Disclosures William N. Bennett, V, MD, Abbvie (Shareholder)Amgen (Shareholder)Nabriva (Shareholder)