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Recurrent uncomplicated lower urinary tract infection in a non-pregnant woman — MSRA MCQ

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HardUrinary Tract InfectionsRecurrent uncomplicated lower urinary tract infection in a non-pregnant womanMSRA

A 38-year-old woman has had three culture-confirmed episodes of uncomplicated lower UTI in the past 9 months. Each episode developed within 24 hours of vaginal intercourse. She is currently asymptomatic; her most recent episode resolved fully after culture-directed treatment 3 weeks ago. Increased fluid intake, avoiding delayed post-coital voiding and spermicide avoidance have not reduced recurrence. Vaginal oestrogen is not appropriate. She wishes to avoid continuous antibiotics. Her previous urine cultures grew Escherichia coli resistant to trimethoprim and susceptible to nitrofurantoin and cefalexin. Her eGFR is stable at 43 mL/minute/1.73 m². She is not pregnant and has no fever, loin pain, urinary tract abnormality or history of upper UTI. Which is the most appropriate prophylactic regimen now?

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Correct answer: C — Cefalexin 500 mg as a single dose after intercourse

This is recurrent uncomplicated lower UTI with a clear, consistent trigger: vaginal intercourse. After behavioural measures have failed, NICE advises considering single-dose antibiotic prophylaxis for use following an identifiable trigger, rather than proceeding directly to continuous prophylaxis. Antibiotic choice should be informed by recent culture susceptibility. Cefalexin 500 mg as a single post-trigger dose is therefore appropriate. Although nitrofurantoin would otherwise be a first-choice agent for trigger-based prophylaxis, NICE specifies its use for prophylaxis only where eGFR is 45 mL/minute or more; this patient’s stable eGFR is 43 mL/minute/1.73 m². Trimethoprim is unsuitable because her previous isolates are resistant. Nightly cefalexin is a continuous prophylactic strategy and is premature when a trigger-specific regimen is appropriate and preferred. Methenamine hippurate is an alternative to daily antibiotic prophylaxis in non-pregnant women, but NICE positions it after recurrent UTI has not improved with behavioural measures, vaginal oestrogen or single-dose prophylaxis where applicable. She should be reviewed within 6 months and advised to seek assessment promptly if she develops symptoms of an acute UTI.

Reference: NICE NG112: Urinary tract infection (recurrent): antimicrobial prescribing — recommendations (Last updated 12 December 2024) — https://www.nice.org.uk/guidance/ng112/chapter/recommendations NICE NG112 visual summary: Choice of antibiotic or antiseptic for recurrent UTI prophylaxis (2024) — https://www.nice.org.uk/guidance/ng112/resources/visual-summary-pdf-6544163629 NICE NG112: Methenamine hippurate recommendations (Last updated 12 December 2024) — https://www.nice.org.uk/guidance/ng112/chapter/recommendations