1187. Retrospective and Prospective Analysis of Acinetobacter Modern-Day Clinical Isolates in a Large Mid-West Hospital System

BACKGROUND: The epidemiology of contemporary Acinetobacter calcoaceticus-baumannii complex (AcbC) strains in the United States is understudied. In addition to increasing multidrug resistance, there is concern that the rates of AcbC infections acquired outside of hospitals and the anatomic distribution of these infections may differ from what is previously reported. Furthermore, the epidemiology of non-AcbC clinical isolates is poorly characterized. METHODS: We retrospectively identified all cases associated with Acinetobacter clinical isolates in the Barnes-Jewish/Children’s Hospital system (St. Louis, MO) from 2007 to 2017. First isolates were classified as AcbC or non-AcbC. Tissue of origin, hospital-day of isolation, and antibiotic resistance profiles were determined. Results were compared with an ongoing prospective analysis of Acinetobacter isolates in the same system, started in July 2017. RESULTS: We identified 2,959 and 1,243 cases associated with AcbC and non-AcbC isolates, respectively. In both groups, isolates were most commonly obtained from respiratory (34% and 30% of total isolates) and connective tissue (34% and 27% of total isolates) sites. Urinary tract specimens were more likely to occur among AcbC isolates compared with non-AcBC isolates (664/2,959 [22%] vs. 147/1,243 [12%], P < 0.001). The percentage of isolates obtained prior to hospital-day-2 are 62% and 78% for AcbC and non-AcbC isolates, respectively. AcbC isolates were markedly more resistant to all classes of antibiotics. Analysis of 77 AcbC and 58 non-AcbC prospectively collected isolates revealed similar clinical findings. CONCLUSION: Our study confirms the protean nature of Acinetobacter clinical isolates, and begins to describe relevant differences between AcbC and non-AcbC strains. These distinctions support the practice of identifying clinical isolates using AcbC and non-AcbC labels. Ongoing studies will further describe the patient characteristics and clinical outcomes associated with Acinetobacter disease in our system. DISCLOSURES: All authors: No reported disclosures.