Fosfomycin

證據等級: L5

預測適應症: 10 個

Fosfomycin: From Urinary Tract Infections to Gonococcal Urethritis

One-Sentence Summary

Fosfomycin is a broad-spectrum antibiotic that inhibits bacterial cell wall synthesis, internationally approved for the treatment of urinary tract infections. The TxGNN model predicts it may be effective for Gonococcal Urethritis, with 6 publications (including 1 RCT) currently supporting this direction — particularly relevant in the era of multidrug-resistant Neisseria gonorrhoeae.

Quick Overview

Item	Content
Original Indication	Urinary tract infections (no Philippines-approved indication on record)
Predicted New Indication	Gonococcal Urethritis
TxGNN Prediction Score	99.99%
Evidence Level	L2 (1 completed RCT)
Philippines Market Status	✗ Not marketed
Number of Registrations	0
Recommended Decision	Proceed with Guardrails

Why is This Prediction Reasonable?

Fosfomycin is a phosphonic acid-derivative antibiotic with a unique mechanism of action: it inhibits MurA (UDP-N-acetylglucosamine enolpyruvyl transferase), the enzyme catalysing the first committed step in bacterial peptidoglycan (cell wall) synthesis. Because this target is distinct from those of β-lactams, fluoroquinolones, and aminoglycosides, fosfomycin retains activity against many multidrug-resistant organisms.

Gonococcal urethritis is caused by Neisseria gonorrhoeae, a Gram-negative diplococcus that synthesises peptidoglycan and is therefore susceptible to cell wall–targeting agents. Fosfomycin has demonstrated in vitro bactericidal activity against N. gonorrhoeae, including strains resistant to ceftriaxone and azithromycin — the current first-line regimen. Given the WHO designation of N. gonorrhoeae as a “high priority” pathogen for new antibiotic development, fosfomycin represents a mechanistically plausible alternative.

The connection between fosfomycin’s established urinary tract indication and gonococcal urethritis is direct: both are bacterial infections of the genitourinary tract, and the drug achieves high local concentrations in urine and urethral tissue. A 2016 open-label RCT (PMID 27064136) specifically evaluated fosfomycin trometamol in uncomplicated gonococcal urethritis in men, lending clinical credibility to the TxGNN prediction.

Clinical Trial Evidence

Currently no clinical trials registered on ClinicalTrials.gov specifically for fosfomycin in gonococcal urethritis.

Note: The 2016 RCT by Yuan et al. (PMID 27064136) was conducted in China and may have been registered in a regional registry. The absence from ClinicalTrials.gov does not negate the published RCT evidence.

Literature Evidence

PMID	Year	Type	Journal	Key Findings
27064136	2016	RCT	Clin Microbiol Infect	Open-label RCT in 152 men with gonococcal urethritis; fosfomycin trometamol 3 g on days 1, 3, 5 vs. standard therapy; 126 patients completed the study — demonstrates direct clinical efficacy data
832528	1977	Clinical Study	Chemotherapy	70 patients with acute/subacute gonococcal urethritis treated with IM fosfomycin; 4 g single dose achieved 86% cure rate (37/43); 4 g split dose achieved 92% cure rate (11/12)
832523	1977	Microbiological Study	Chemotherapy	Bacteriological evaluation of fosfomycin across 959 patients in multi-centre controlled studies; gonococcal urethritis included as one of the clinical indications evaluated
35820778	2023	Secondary Analysis	Sex Transm Infect	NABOGO trial secondary analysis assessing spontaneous clearance of asymptomatic N. gonorrhoeae; provides context on natural history relevant to treatment trial design
19593988	2009	Review	Zhonghua Nan Ke Xue	Review of diagnosis and treatment of genitourinary infection with non-gonococcal Neisseria in men; provides differential diagnostic context
17878816	2007	Case Report	J Fr Ophtalmol	Case of gonococcal conjunctivitis with MDR N. gonorrhoeae (resistant to penicillins, tetracyclines, fluoroquinolones); illustrates the growing need for alternative agents

Philippines Market Information

Fosfomycin currently has no registered products in the Philippines. There are no active authorizations from the Philippines FDA on record.

Implication: Any repurposing initiative would first require regulatory pathway assessment for product registration or compassionate use/special access programme eligibility.

Safety Considerations

Please refer to the package insert for safety information. Key warnings, contraindications, and drug interaction data were not available in the current evidence pack.

General considerations based on international labelling:

Fosfomycin trometamol (oral) is generally well tolerated; the most common adverse effects are gastrointestinal (diarrhoea, nausea)
IV fosfomycin may cause electrolyte imbalances (hypokalaemia, hypernatraemia) due to the sodium content of the disodium salt formulation
Allergic reactions are rare but possible

Conclusion and Next Steps

Decision: Proceed with Guardrails

Rationale: The TxGNN prediction score is extremely high (99.99%), and — critically — direct clinical evidence already exists: a 2016 RCT and a 1977 clinical study both evaluated fosfomycin specifically for gonococcal urethritis with favourable cure rates. The mechanistic link is strong and well-characterised (cell wall synthesis inhibition active against N. gonorrhoeae). In the context of rising multidrug-resistant gonorrhoea, fosfomycin addresses a genuine unmet clinical need.

To proceed, the following is needed:

Philippines regulatory pathway: Assess feasibility of product registration or importation under special access, since fosfomycin is currently not marketed in the Philippines
Updated in vitro susceptibility data: Test local N. gonorrhoeae isolates against fosfomycin to establish regional MIC distributions
Mechanism of action (MOA) formal documentation: Obtain detailed MOA data from DrugBank to complete the pharmacological profile
Safety profile (package insert): Obtain and parse the full prescribing information for warnings, contraindications, and drug interactions
Optimal dosing regimen: The 2016 RCT used a multi-dose oral regimen (3 g × 3 doses); further PK/PD modelling may identify the minimum effective regimen
Antimicrobial resistance monitoring: Establish baseline fosfomycin resistance rates in regional N. gonorrhoeae populations before large-scale use

Appendix: Other TxGNN Predicted Indications

Rank	Disease	Score	Evidence Level	Recommendation	Rationale
1	Gonococcal urethritis	99.99%	L2	Proceed with Guardrails	Strong mechanistic link; 1 RCT + clinical studies
2	Ureaplasma urethritis	99.99%	L5	Hold	⚠️ Mechanistic contradiction: Ureaplasma lacks cell wall — fosfomycin has no expected activity
3	Uterine inflammatory disease	99.98%	L4	Research Question	Partial mechanistic link; PID involves mixed pathogens, some susceptible
4	Xanthogranulomatous pyelonephritis	99.98%	L5	Research Question	Plausible (active against causative organisms) but surgery is mainstay
5	Epiglottitis	99.93%	L5	Hold	Established treatments exist; fosfomycin offers no advantage
6	Urogenital tuberculosis	99.88%	L5	Hold	⚠️ Weak mechanistic link: M. tuberculosis cell wall differs; high MICs
7	Laryngitis	99.68%	L4	Hold	Mostly viral aetiology; limited evidence for nebulised fosfomycin
8	Hyperamylasemia	99.47%	L5	Hold	⚠️ False positive: non-infectious laboratory finding
9	Polyclonal hyperviscosity syndrome	99.47%	L5	Hold	⚠️ False positive: immunological/haematological condition
10	Pyelitis	99.37%	L1	Proceed with Guardrails	Core indication area; Phase 2/3 RCT (ZEUS trial) + 20 publications

Notable: Rank 10 (Pyelitis) has the strongest evidence base (L1) with a completed Phase 2/3 RCT and 20 publications, representing fosfomycin’s established therapeutic territory in upper urinary tract infections.

This report is for research purposes only and does not constitute medical advice. Drug repurposing candidates require clinical validation before application.

Report generated: 2026-04-05 | Evidence Pack version: v4 | Data cutoff: 2026-04-05

Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.