2420. A Real-World Perspective on the Efficacy of Fosfomycin for Treatment of Multidrug-Resistant Pathogens Causing Urinary Tract Infections

BACKGROUND: Urinary tract infections (UTI) are the most common infection associated with multidrug-resistant (MDR) pathogens. With limited treatment options, there has been an increasing interest in the efficacy of fosfomycin (FOS); however, real-world clinical data are limited. Our objective was to assess the outcomes of hospitalized patients with MDR UTIs treated with FOS. METHODS: Retrospective review of patients with carbapenem-resistant (CRE) or extended spectrum β-lactamase producing (ESBL) Enterobacteriaceae, or vancomycin-resistant Enterococcus (VRE) UTIs who received ≥1 dose of FOS. UTI was defined as a urine culture with ≥1000 CFU/mL among patients with dysuria, increased urinary frequency, suprapubic or flank pain or tenderness, fevers, or altered mental status without an alternative etiology. We defined cure as resolution of symptoms within 7 days without reoccurrence within 30 days. Microbiological failure was defined as a positive urine culture within 14 days. RESULTS: 49 patients with MDR UTIs (17 ESBL, 17 VRE, 15 CRE) were included. Median age was 69 (range: 20–95), 18% were male, 14% were immunosuppressed and the median Charlson score was 4 (0–12). 33% had indwelling catheters and 10% of patients had neurogenic bladder. Increased frequency (29%) and fever (27%) were the most common symptoms. 51% of cases were healthcare associated and 64% met the CDC/NHSN definition of UTI. UTIs were complicated by pyelonephritis in 2 patients, but none had concomitant bacteremia. FOS was administered as empiric or definitive treatment in 39% and 61%, respectively. Only 12% of patients received >1 dose. Cure occurred in 88% of patients, and did not vary by infecting pathogen (Figure 1, Table 2), or the number of FOS doses received. Patients with relapsing symptoms were infected by ESBL (n = 3), CRE (n = 1), and VRE (n = 3); all but one received 1 dose of FOS. Microbiologic failures occurred in 18% due to ESBL (n = 1), CRE (n = 4), and VRE (n = 4). 4% of patients died in-hospital, but only 1 death was related to UTI. Overall, FOS was well-tolerated with vomiting recorded in one patient. CONCLUSION: Across a range of MDR pathogens causing UTIs, FOS was well-tolerated and effective for hospitalized patients. FOS represents an attractive oral option to preserve alternative agents for systemic infections. Future studies are needed to evaluate the benefit of repeated dosing. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.