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Fosfomycin in CKD UTI — SCE Infectious Diseases MCQ

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ModerateAntimicrobial StewardshipFosfomycin in CKD UTISCE Infectious Diseases

A 50-year-old man with chronic kidney disease (eGFR 22 mL/min) develops a UTI caused by ESBL-producing E. coli. He has simple cystitis (no systemic features). Sensitivities show: Nitrofurantoin sensitive, Fosfomycin sensitive, Pivmecillinam sensitive. eGFR is 22. Which oral agent can still be used?

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Correct answer: B — Fosfomycin 3 g single dose — it does not require dose adjustment in renal impairment and achieves adequate urinary concentrations even with low GFR

At eGFR <45 mL/min, Nitrofurantoin is contraindicated (ineffective at low urinary concentrations + systemic accumulation risk). At eGFR <30, Pivmecillinam may have reduced efficacy. Fosfomycin (Fosfomycin Trometamol 3 g single oral dose) achieves adequate urinary concentrations even in moderate-severe renal impairment and does not require dose adjustment. It is therefore a valuable option for ESBL cystitis in CKD. However, it should only be used for uncomplicated cystitis (not bacteraemia or pyelonephritis due to inadequate serum levels).

Reference: NICE NG109 2018 – UTI; BNF 2024 – Fosfomycin; EUCAST 2024