2263. Fosfomycin Trometerol Use for Complicated UTIs Including Pyelonephritis, a 1-year Review of Outcomes and Prescribing Habits

BACKGROUND: Treatment of complicated urinary tract infections (UTI) caused by multidrug-resistant organisms (MDROs) is increasingly problematic given limited oral antibiotic options. In these situations, fosfomycin is increasingly used. However, there are limited outcome and pharmacokinetic data to support fosfomycin use for complicated UTIs (cUTI), especially in the upper tract. We describe fosfomycin use for complicated cUTI in our healthcare system. METHODS: We performed a retrospective review of all fosfomycin prescriptions between 1/1-December 31/17 in the Los Angeles Department of Health Service system, which consists of 4 medical centers and 19 clinics that provide care to >600,000 patients annually. In our system, fosfomycin use requires ID approval. We collected demographics, clinical characteristics, adverse effects, and 30-day success rates. Subsequent urine cultures up to December 31/18 were examined for fosfomycin susceptibility. RESULTS: A total of 156 patients received fosfomycin; 21 (13%) had lower UTI, 39 (25%) had lower tract cUTI, 24 (15%) had upper tract not pyelonephritis, and 37 (24%) had pyelonephritis. The majority (n = 98, 63%) were female, 82 (53%) had urological or functional abnormalities, 67 (43%) had diabetes, 26 (17%) were immunocompromised and most (n = 135, 87%) presented from the community. E.coli was the predominant pathogen (n = 123, 79%), 112 (91%) of these produced ESBL. For cUTI (n = 100), dosing interval was q24h (3%), q48h (51%) and q72h (46%). Among patients with 30-day outcomes (n = 100, 64%), success was seen in 84 (84%), and was 79% (14/64) among those with cUTI. Failure was associated with male gender (p = 0.005), urological abnormalities (p = 0.047), and non-E. coli UTIs (p = 0.03). Only 1 adverse effect at 30 days was described. Fosfomycin-resistant E. coli were found in 9/64 (14%) of patients with follow-up urine cultures > 30 days after initial treatment (mean 5.7 ± 4.03 mo.). CONCLUSION: Despite the lack of data supporting its use, we found that most patients receiving fosfomycin for complicated upper UTIs had clinical success. However, emergence of subsequent resistance warrants caution. Further studies should be done to better understand optimal use of fosfomycin for complicated UTIs. DISCLOSURES: All authors: No reported disclosures.