1581. The Use of Oral fosfomycin in Veterans for the Treatment of Urinary Tract Infections Caused by Multidrug Resistant Gram-negative Organisms
Session: Poster Abstract Session: Clinical Infectious Diseases: UTIs
Saturday, October 10, 2015
Room: Poster Hall
Background: Oral therapeutic options for the treatment of urinary tract infections (UTIs) have become limited due to the emergence of Gram-negative bacteria resistant to fluroquinolones, sulfonamides and beta-lactams. Fosfomycin is one of the few oral agents to treat UTIs caused by multidrug resistant Gram-negative bacteria. Data indicating the activity and efficacy of fosfomycin in our population is limited. The primary objective of this study is to determine the clinical response of patients treated with oral fosfomycin for UTIs caused by Gram-negative organisms. Secondary objectives include determining bacterial susceptibility to fosfomycin and microbiological response.

Methods: A retrospective chart review was conducted on patients who received at least one dose of oral fosfomycin for a UTI caused by a Gram-negative organism. Clinical response was classified as favorable, unfavorable, or uncertain. Microbiological response was defined as cured, presumed cured, or failed.  For patients whose bacterial isolate was available, susceptibility of fosfomycin was determined using the disk diffusion method performed and interpreted according to Clinical Laboratory Standards Institute (CLSI) recommendations

Results: Seventy-three patients received fosfomycin from January 2005-April 2014. Fifty (68.5%) of patients achieved a favorable clinical response. As for microbiological response, the results were similar; fifty patients attained a cure or presumed cure. Veterans with an E. coli infection achieved a favorable response rate of 80%, whereas veterans with a P. aeruginosa or K. pneumoniae infection only achieved a favorable response rate of 61.5% and 60%, respectively. Fosfomycin susceptibility was determined on twenty-two isolates (9 Klebsiella pneumoniae, 8 Escherichia coli, 5 Pseudomonas aeruginosa). All isolates were susceptible according to CLSI disk diffusion breakpoints except for two K. pneumoniae isolates.

Conclusion: Fosfomycin has retained activity against many Gram-negative organisms; achieving fair clinical and microbiological response rates. Fosfomycin appears to be most efficacious in E. coli UTIs. Further study is needed to clarify the microbiological and clinical determinants of therapeutic failure.

Leanne Moore, Pharm.D., Pharmacy, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, Federico Perez, MD, Medicine, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, Christopher Burant, Ph.D., Geriatric Research Education and Clinical Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH and Sharanie Sims, Pharm.D., BCPS (AQ-ID), Pharmacy, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH


L. Moore, None

F. Perez, None

C. Burant, None

S. Sims, None

Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.