Treatment of MDR urinary tract infections with oral fosfomycin: a retrospective analysis

Limited options for treating MDR organisms have led clinicians to turn to older antimicrobial agents that may display activity against such infections. One such agent is fosfomycin, an oral drug with activity against a variety of Gram-positive and -negative bacteria, but only approved for use in the USA for urinary tract infection (UTI) due to Escherichia coli and Enterococcus faecalis. The purpose of this study was to assess the efficacy of fosfomycin treatment of MDR UTI and identify predictors of outcome. A retrospective review was performed of patients treated for MDR UTI at a large quaternary medical centre between 1 January 2010 and 30 September 2014. Sixty patients received 69 courses of fosfomycin in the inpatient or outpatient setting for UTIs due to Enterobacteriaceae, Pseudomonas aeruginosa or VRE. In the 58 patients for whom follow-up data were available, the treatment success rate (no persistent or recurrent infection) was 55%. Chronic kidney disease was associated with persistent infection (ORaEuroS=aEuroS3.56, 95% CIaEuroS=aEuroS1.02-12.40, PaEuroS=aEuroS0.04). No other factors, including comorbidities, infecting organism, fosfomycin MIC or number of doses of fosfomycin received, were associated with recurrent infection or treatment failure. This study supports the use of fosfomycin as an oral option for treating MDR UTIs. Additional studies are required to assess the optimal dosing and utility of combination therapy to decrease the incidence of treatment failure.