What is the use of Fosfomycin (antibiotic)?

From the Guidelines

Fosfomycin is a recommended treatment option for uncomplicated urinary tract infections (UTIs), particularly due to its effectiveness against common UTI-causing bacteria like E. coli and its unique mechanism of action that differs from other antibiotics, as noted in the 2022 guidelines 1. The standard dosage for adults is 3 grams as a single-dose powder that is dissolved in water and taken by mouth. This one-time treatment is particularly effective and achieves high concentrations in the urinary tract, maintaining activity for 24-48 hours after a single dose. Some key points to consider when prescribing fosfomycin include:

• It should be taken on an empty stomach or at least 2-3 hours after a meal for optimal absorption.
• Common side effects include diarrhea, headache, and nausea, which are typically mild and transient.
• Fosfomycin is generally well-tolerated and particularly useful for pregnant women and patients with allergies to other antibiotics, though it should be avoided in those with severe kidney impairment. According to the 2011 guidelines 1, fosfomycin trometamol (3 g in a single dose) is an appropriate choice for therapy where it is available due to minimal resistance and propensity for collateral damage. However, the most recent guidelines from 2022 1 recommend a single dose of fosfomycin 3 g PO for uncomplicated urinary tract infections due to multidrug-resistant organisms, which further supports its use in this context. Overall, fosfomycin is a viable treatment option for uncomplicated UTIs, particularly in cases where other antibiotics may not be effective or suitable, as supported by the latest guidelines 1.

From the FDA Drug Label

Fosfomycin tromethamine granules for oral solution is indicated only for the treatment of uncomplicated urinary tract infections (acute cystitis) in women due to susceptible strains of Escherichia coli and Enterococcus faecalis. The main use of Fosfomycin is for the treatment of:

• Uncomplicated urinary tract infections (acute cystitis) in women
• Due to susceptible strains of:
  • Escherichia coli
  • Enterococcus faecalis 2

From the Research

Fosfomycin Overview

• Fosfomycin is an oral antimicrobial agent used to treat urinary tract infections (UTIs) 3, 4, 5.
• It has shown in vitro activity against multidrug-resistant (MDR) urinary pathogens, including Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa 4, 6.

Efficacy of Fosfomycin

• A retrospective study found that fosfomycin achieved clinical success in 96.4% of patients with complicated or MDR UTIs 3.
• Another study found that fosfomycin had a microbiological cure rate of 59% in patients with UTIs due to MDR pathogens 6.
• A randomized clinical trial found that fosfomycin was not noninferior to comparators (ceftriaxone or meropenem) in the treatment of bacteremic UTIs due to MDR E coli, but may be considered for selected patients 7.

Fosfomycin Susceptibility

• Fosfomycin has shown good in vitro susceptibility against common uropathogens, including MDR isolates 4, 6.
• A study found that fosfomycin had a susceptibility rate of 94% against gram-negative and gram-positive uropathogens 4.
• Another study found that fosfomycin had a susceptibility rate of 86% against MDR pathogens, including carbapenem-resistant Klebsiella pneumoniae and vancomycin-resistant Enterococcus faecium 6.

Clinical Use of Fosfomycin

• Fosfomycin is indicated for the treatment of uncomplicated lower urinary tract infections (UTIs) 5.
• It can be used as a single-dose treatment for acute cystitis, with a therapeutic concentration in the urine for one to three days 5.
• Fosfomycin is well tolerated and appears safe for use during pregnancy 5.