What is the recommended treatment for uncomplicated urinary tract infections using Fosfomycin?

Fosfomycin Treatment for Uncomplicated Urinary Tract Infections

A single 3-gram oral dose of fosfomycin tromethamine is the recommended treatment for uncomplicated urinary tract infections (acute cystitis) in women due to susceptible strains of Escherichia coli and Enterococcus faecalis. 1

Dosing and Administration

• Fosfomycin is administered as a single 3-gram sachet of granules that must be dissolved in water before ingestion 1
• The medication can be taken with or without food 1
• This single-dose regimen provides therapeutic urinary concentrations for 24-48 hours 2
• Peak urinary concentrations occur within 4 hours and remain high (>128 mg/L) for 24-48 hours, which is sufficient to inhibit most urinary tract pathogens 3

Efficacy

• Clinical efficacy rates for fosfomycin in treating uncomplicated UTIs are approximately 91%, with microbiological efficacy rates around 80% 4
• While bacterial efficacy of fosfomycin is somewhat lower than some other first-line agents, clinical efficacy is comparable 4, 2
• Bacteriological eradication rates of 75-90% are typically achieved 5-11 days after therapy 3
• The European Association of Urology recommends fosfomycin as a first-line treatment option for uncomplicated cystitis in women 2

Advantages and Considerations

• The convenience of a single-dose regimen improves patient adherence 4, 2
• Fosfomycin has minimal propensity for collateral damage to intestinal flora 4
• The drug shows in vitro activity against multidrug-resistant pathogens, including vancomycin-resistant enterococci (VRE) 4
• A single 3-gram oral dose is also recommended for uncomplicated UTIs caused by VRE 4

Comparison with Other Agents

• Fosfomycin has comparable clinical efficacy to nitrofurantoin but with the advantage of single-dose administration versus multiple-day regimens 2, 5
• In comparative studies with ciprofloxacin, cotrimoxazole, and nitrofurantoin, clinical cure rates were similar 3
• A meta-analysis found no significant differences in clinical cure (RR 0.95% CI 0.81-1.12) and microbiological cure (RR 0.96,95% CI 0.84-1.08) between fosfomycin and nitrofurantoin 6

Safety Profile

• Fosfomycin is generally well tolerated with a low incidence of adverse events 3
• The most common side effects are gastrointestinal symptoms including diarrhea (2.4%), nausea, and headache 4, 5
• These adverse events are typically transient, mild, and self-limiting 3

Important Limitations

• Fosfomycin is indicated only for uncomplicated UTIs (acute cystitis) in women 1
• It is not indicated for the treatment of pyelonephritis or perinephric abscess 1
• If bacteriuria persists or recurs after treatment, alternative therapeutic agents should be selected 1
• The presence of high-level resistant subpopulations at baseline may predict treatment failure, with a disk diffusion zone of <24 mm being a better predictor for baseline heteroresistance and regrowth 7

Follow-up Recommendations

• Routine post-treatment urinalysis or urine cultures are not indicated for asymptomatic patients 2
• If symptoms do not resolve by the end of treatment or recur within 2 weeks, urine culture and antimicrobial susceptibility testing should be performed 2