Background: With repeated exposure to antimicrobials, development of MDR bacterial infections pose a serious clinical problem in organ transplant recipients. Generally, these type of infections require hospital admission and treatment with intravenous antibiotics. An effective oral agent for out-patient treatment could significantly reduce length of hospitalization and cost of care. Fosfomycin, a bactericidal phosphoric acid derivative with activity against a wide range of gram positive and gram negative bacteria, offers a viable treatment modality. The objective of this study was to examine the outcomes of fosfomycin therapy for the treatment of MDR UTIs in organ transplant recipients.

Methods and Reults: 15 episodes of UTIs in 12 patients treated with fosfomycin between January 2009 and November 2012 were reviewed. Study subjects consisted of 10 kidney transplant, 1 liver transplant, and 1 simultaneous kidney and pancreas recipients. Baseline characteristics are listed in table 1.

The pathogens included 8 E. coli isolates (including 2 carbapenemase-producing, 5 ESBL-producing), 6 Klebsiella pneumoniae (4 carbapenemase-producing, 2 ESBL-producing), and 1 Serratia marcescens. Fosfomycin 3 gram every 48 hours were given with mean of 5.2 ± 1.3 doses per treatment course. Overall treatment response rate was 86%; 53% being microbiological response (negative follow up urine culture) and 33% clinical response (lack of available repeat urine culture but no clinical relapse). Two patients experienced relapses requiring additional courses of fosfomycin, one with neurogenic bladder and the other with prolonged urethral catheter.

Conclusion: The results of our study suggest that oral fosfomycin is an effective alternative to available intravenous antibiotics for treatment of MRD UTIs in solid organ transplant recipients. Judicious use of this agent in this patient population could reduce the burden of MDR infections in the healthcare system.

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