Fosfomycin

How it works

It inhibits MurA (enolpyruvyl transferase), the first committed enzyme in bacterial cell wall peptidoglycan synthesis, giving broad activity including against many resistant Gram-negative organisms.

Prescribing in practice

• Reserve fosfomycin for confirmed or strongly suspected resistant urinary infection in line with antimicrobial stewardship, as it is a valued agent for multidrug-resistant organisms.
• The oral granules are dissolved in water and best taken on an empty stomach, ideally at bedtime after emptying the bladder, to maximise urinary concentrations.
• The intravenous preparation carries a significant sodium load, which is relevant in heart failure and where sodium restriction matters.

Monitoring

Routine monitoring is limited for single oral doses, but electrolytes including sodium and potassium should be checked during intravenous courses.

Counselling the patient

• Dissolve the granules in water and drink immediately, preferably at night after passing urine.
• A single dose is usually enough; return if symptoms persist or worsen.
• Take it on an empty stomach for best effect.

Evidence & guidelines

Single-dose oral fosfomycin trometamol is recommended in NICE urinary tract infection guidance as an option for lower UTI, including some resistant organisms.