Perioperative Disodium Fosfomycin in the Prophylaxis of Urinary Tract Infection in Kidney Transplant Recipients. Controlled Clinical Trial (PERIFOS Trial)

In the context of development UTI in receptors of KT, some microbiological factors have raised great importance, mainly the antimicrobial drug resistance, which has been reported for TMP/SMX as high as 60 to 100%. Furthermore, it is also of increasing importance the recent isolation of multidrug-resistant bacteria, in particular ESBL-producing Escherichia coli and ampicillin-resistant Enterococcus. This phenomenon increases the rate of hospitalizations as well as the costs of hospital stay and antibiotic therapy. (1-3) In our institution, in receptors of KT the rate of TMP/SMX resistance is 89% and ESBL-production about 32% among E. coli recovered from urine. (4)

Because of the increase in the rate of TMP-SMX resistance, there is a lot of interest to use other antibiotics for the prevention of UTI among different populations. In this sense, fosfomycin is an agent with a unique mechanism of action that does not share with other families of known antibiotics, this characteristic provides advantages to use this antibiotic alone or, even, synergistically in combination with other antibiotics. Fosfomycin (FOS) is a wall antibiotic (pyruvyl-transferase inhibitor) that has shown a good bioavailability, especially in the urinary tract. It has shown a wide antibacterial spectrum, but the important target seems to be enteric bacilli particularly Escherichia coli (the most prevalent cause of UTI). FOS has also shown a very good activity against E. coli producer of Extended Spectrum Betalactamases.

Multiple clinical studies have shown FOS efficacy in the treatment of UTI's and especially in multiple-drug-resistant bacteria. (5) With regard to its use as a perioperative prophylaxis, in a systematic review with 8 trials, FOS proved to be effective to prevent health care-associated UTI's, however only one study showed no benefit. The oral dose regularly used is FOS 3 g, 3 hours before and 24 hours after the surgical procedure. (6)

Our hypothesis is that in the seven weeks after kidney transplantation, perioperative prophylaxis with FOS will show greater efficacy in comparison with standard prophylaxis (TMP/SMX). Considering that the mean number of UTI and BA episodes per patient in the first seven weeks is 0.8 episodes / patient, if we want to decrease it to 0.4 episodes per patient, using the means comparison formula will require 40 patients per arm per treatment, this considering a power of 80% and confidence intervals of 95%. The primary outcome will be to compare the mean number of episodes of urinary tract infection and asymptomatic bacteriuria per patient in each treatment arm. Secondary outcomes refer to the development of UTI-associated sepsis, pyelonephritis, recurrent UTI and asymptomatic bacteriuria. Safety outcomes included hematological and gastrointestinal side effects, the acute rejection rate, glomerular filtration rate, graft loss and patient death.

Patients eligible for a kidney transplant will be invited to participate in the study, prior to renal transplant surgery. They are given an informed consent, which is reviewed and approved by the ethics and research committees of our institution. The arms of the study are discussed in detail below. The study followed the Declaration of Helsinki recommendations and was approved by the Institutional Review Board (Ref: 1649). Randomization was conducted centrally by stratifying according to gender, with specific software (www.randomization.com). Patients were assigned to one of two parallel groups in a 1:1 ratio and in blocks of 4.