Fosfomycin for the treatment of drug-resistant urinary tract infections: potential of an old drug not explored fully.

INTRODUCTION

Increased emergence of bacterial resistance and the limited options of novel antimicrobial agents have necessitated the reintroduction of some old antimicrobial agents. One such drug is fosfomycin, but its potential has not been explored fully, especially in India.

AIMS AND OBJECTIVES

To analyze the in vitro activity of fosfomycin, against the urinary isolates and to compare it with in vitro activity of other orally administered antimicrobial agents.

MATERIALS AND METHODS

This was a prospective observational study conducted between July 2014 and June 2016. All consecutive, non-duplicate and clinically significant urinary isolates obtained from patients of all ages and both genders, diagnosed to have UTI, were included. Patients already on antibiotic therapy were excluded. Urine culture was performed by semiquantitative method on cysteine lactose electrolyte-deficient medium and the isolates obtained in significant count were subjected to antimicrobial sensitivity testing by the Kirby Bauer disk diffusion method as per CLSI guidelines.

RESULTS

A total of 3947 non-repeating urinary isolates were included in the study, of which 2684 (68%) isolates originated from adult outpatients and remaining 1236 (32%) isolates from pediatric patients. Of these 2783 isolates were from enterobacteriaceae family. Out of these 2730 (98.1%) were sensitive to fosfomycin. Most [375 of 385 (97.4%)] Pseudomonas spp were also susceptible to fosfomycin. A majority of ESBL- (96.5%) and MBL (91.9%)-producing isolates were also susceptible to fosfomycin and so were of Gram-positive isolates [698/707 (96%)] and MRSA [61/69 (88.4%)] were susceptible to fosfomycin.

CONCLUSIONS

Fosfomycin showed an excellent in vitro activity against all urinary pathogens, including the Gram-positive or Gram-negative, ESBL and MBL producers. Fosfomycin should be considered as a highly effective alternative in treatment UTIs in both adults and pediatric patients.