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Recurrent uncomplicated lower urinary tract infection — MSRA MCQ

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HardUrinary Tract InfectionsRecurrent uncomplicated lower urinary tract infectionMSRA

A 61-year-old postmenopausal woman has had four culture-confirmed lower urinary tract infections in the past 12 months. The episodes have no consistent relationship to sexual intercourse or any other identifiable trigger. Behavioural measures and vaginal oestrogen have not reduced their frequency. Specialist assessment and urinary tract ultrasonography found no structural or functional abnormality. She now presents with marked dysuria, frequency and urgency. She is afebrile, systemically well and has no loin pain or vomiting. A midstream urine sample is sent for culture. Her eGFR is 68 mL/minute/1.73 m², liver function is normal, and she has no history of gout. She regularly uses over-the-counter potassium citrate sachets for urinary symptoms and wishes to minimise further antibiotic exposure. Which is the most appropriate management plan?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — Treat the acute infection, then commence methenamine hippurate and stop potassium citrate

Explanation lettering: E = shown as A · A = shown as B · D = shown as C · B = shown as D · C = shown as E

The symptomatic acute lower UTI should first be treated appropriately; methenamine hippurate is a preventive treatment and should be started after the current infection has been adequately treated. She is then eligible for methenamine because she is not pregnant, has recurrent uncomplicated lower UTI, has completed appropriate investigation, and has not improved with behavioural measures or vaginal oestrogen. It also accords with her preference to minimise antibiotic exposure. Potassium citrate alkalinises the urine and reduces methenamine's effectiveness, so the sachets must be stopped when methenamine is commenced. A is plausible because single-dose prophylaxis can limit total antibiotic exposure, but it is used when infections follow an identifiable trigger; her infections are not related to intercourse. B is an established option and her eGFR permits nitrofurantoin, but methenamine is the better antibiotic-sparing choice before daily antibiotic prophylaxis in this scenario. C is inadequate because vaginal oestrogen has already failed as sole prevention. E causes unnecessary delay: specialist advice is required for groups such as pregnant people or those with recurrent upper or complicated lower UTI, whereas she has already undergone assessment and has uncomplicated recurrent lower UTI. Methenamine should be reviewed within 6 months and annually thereafter.

Reference: Urinary tract infection (recurrent): antimicrobial prescribing — Recommendations (12 December 2024) — https://www.nice.org.uk/guidance/ng112/chapter/recommendations Urinary tract infection (recurrent): antimicrobial prescribing — Methenamine hippurate recommendations (12 December 2024) — https://www.nice.org.uk/guidance/ng112/chapter/recommendations Hiprex 1 g Tablets — Summary of Product Characteristics (15 October 2025) — https://www.medicines.org.uk/emc/product/1530/smpc