Can fosfomycin be used to treat complicated urinary tract infections (UTIs) in men?

Fosfomycin for Complicated UTI in Men

Fosfomycin is not recommended as a first-line treatment for complicated UTIs in men according to current guidelines, but may be considered as an alternative option in specific situations where multidrug-resistant pathogens are present and other oral options are limited. 1

Current Guideline Recommendations

The 2024 European Association of Urology (EAU) guidelines clearly state that fosfomycin trometamol is "recommended only in women with uncomplicated cystitis" 1. For men with UTIs, the EAU guidelines specifically recommend trimethoprim-sulfamethoxazole (TMP-SMX) for 7 days as the primary treatment, with fluoroquinolones as an alternative based on local susceptibility patterns 1.

Similarly, the 2021 American College of Physicians (ACP) guidelines do not include fosfomycin in their recommendations for complicated UTIs or for UTIs in men 1. Instead, they recommend:

• For uncomplicated pyelonephritis: fluoroquinolones (5-7 days) or TMP-SMX (14 days)
• For complicated UTIs: treatment based on culture and susceptibility results

Why Fosfomycin Is Not First-Line for Men with UTIs

1. Limited Evidence: Most clinical trials for fosfomycin have focused on women with uncomplicated cystitis
2. Anatomical Differences: Men's UTIs are often complicated by prostate involvement
3. Dosing Concerns: The standard single-dose regimen for uncomplicated cystitis is likely inadequate for complicated infections

Potential Exceptions - When Fosfomycin Might Be Considered

Despite not being first-line, emerging research suggests fosfomycin may have a role in treating complicated UTIs in men in specific scenarios:

1. Multidrug-resistant organisms: When the causative pathogen is resistant to first-line agents but susceptible to fosfomycin 2
2. Patient intolerance: When patients cannot tolerate first-line agents due to adverse effects 3
3. Limited oral options: When other oral antibiotics are not viable due to resistance patterns 4

Modified Dosing for Complicated UTIs

If fosfomycin is used for complicated UTIs in men, the standard single-dose regimen is inadequate. Research suggests:

• For acute complicated UTI: One dose every 24-48 hours for 2-3 weeks 2
• For chronic bacterial prostatitis: One dose every 24-48 hours for approximately 5-6 weeks 2

Efficacy Considerations

Fosfomycin appears to have different efficacy depending on the pathogen:

• E. coli infections: Generally good response rates, with low resistance (1-2.4%) 5, 6
• Klebsiella infections: Higher treatment failure rates and higher resistance rates (up to 19%) 6

Important Caveats

1. Culture and susceptibility testing is mandatory before using fosfomycin for complicated UTIs in men
2. Prostate involvement should be considered in all male UTIs and may require longer treatment durations
3. Monitoring for clinical response is essential, with follow-up cultures recommended

Algorithm for Considering Fosfomycin in Men with UTIs

1. Obtain urine culture and susceptibility testing
2. First consider guideline-recommended treatments (TMP-SMX or fluoroquinolones)
3. Consider fosfomycin only if:
   • Pathogen is resistant to first-line agents but susceptible to fosfomycin
   • Patient cannot tolerate first-line agents
   • Limited oral options are available
4. If using fosfomycin, implement multiple-dose regimen (not single dose)
5. Monitor clinical response closely
6. Consider urological evaluation to rule out anatomical abnormalities

In conclusion, while fosfomycin is not recommended as first-line therapy for complicated UTIs in men, emerging evidence suggests it may have a role as an alternative agent in specific clinical scenarios, particularly for multidrug-resistant infections when options are limited.