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Recurrent uncomplicated lower urinary tract infection — MSRA MCQ

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HardUrologyRecurrent uncomplicated lower urinary tract infectionMSRA

A 67-year-old woman has had five culture-confirmed episodes of lower urinary tract infection during the past 10 months. She has had no fever, loin pain or visible haematuria. Urological assessment, including urinary tract ultrasonography and measurement of post-void residual volume, found no complicating abnormality. Behavioural measures have not reduced the recurrence rate. She has used vaginal oestrogen for 8 months, with improvement in vaginal dryness but three further infections. There is no consistent association with sexual intercourse or another identifiable trigger. Her latest infection has been treated according to susceptibility results, and she is now asymptomatic. Her eGFR is 62 mL/min/1.73 m², liver function is normal, and she has no history of gout. She declines continuous antibiotic prophylaxis but would consider a non-antibiotic medicine. She routinely keeps potassium citrate sachets at home for urinary symptoms. Which is the most appropriate preventive management?

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

Reveal the answer and explanation

Correct answer: D — Start methenamine hippurate 1 g twice daily, stop potassium citrate, and review within 6 months

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

She has recurrent uncomplicated lower UTI despite behavioural measures and an adequate trial of vaginal oestrogen. The current infection has been treated, she is not pregnant, and she wishes to avoid daily antibiotics. NICE therefore supports methenamine hippurate as an alternative to daily antibiotic prophylaxis. The adult dose is 1 g twice daily. Methenamine requires acidic urine to generate its antibacterial effect. Potassium citrate alkalinises the urine and reduces its efficacy, so her symptom-relief sachets must be stopped. Treatment should first be reviewed within 6 months and subsequently every 12 months. A is a plausible antimicrobial prophylaxis regimen, but she has declined continuous antibiotics and methenamine is an appropriate antibiotic-sparing option. C combines methenamine with an interacting alkalinising agent and delays the initial review. D is appropriate only when infection follows an identifiable trigger such as intercourse; no such relationship exists here. E is inadequate because recurrent infections have continued despite vaginal oestrogen. Specialist advice would be required for methenamine in pregnancy, men, children, recurrent upper UTI or complicated lower UTI, none of which applies following her urological assessment.

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