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Fever and suspected urinary tract infection in an infant younger than 3 months — MRCEM SBA MCQ

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HardPaediatric emergenciesFever and suspected urinary tract infection in an infant younger than 3 monthsMRCEM SBA

A 7-week-old infant is brought to the emergency department with a temperature of 38.4°C. She is alert, feeding reasonably well and well perfused. There is no respiratory focus or neurological abnormality. Urine microscopy shows bacteriuria, and a sample has been sent for culture. Her white blood cell count is 16.8 × 10⁹/L and C-reactive protein is 6 mg/L. A blood culture has been taken. She has received no antibiotics, and there is no contraindication to lumbar puncture. What is the most appropriate management plan now?

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

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Correct answer: C — Admit, perform lumbar puncture and give intravenous cefotaxime plus amoxicillin.

The bacteriuria suggests a urinary source, but it does not remove the need to assess this febrile young infant for invasive infection. At 7 weeks, she falls within the 1-to-3-month age group. Her white blood cell count exceeds 15 × 10⁹/L, which is a NICE indication for both lumbar puncture, unless contraindicated, and parenteral antibiotics even though she appears well and her C-reactive protein is low. Perform the lumbar puncture promptly and, when possible, before antibiotics; antibiotic treatment should not be held up by a clinically significant procedural delay. The recommended empirical combination is a third-generation cephalosporin plus an agent active against *Listeria*, such as amoxicillin. Paediatric admission permits treatment and observation while cultures are pending. ([nice.org.uk](https://www.nice.org.uk/guidance/ng143/chapter/recommendations)) A incorrectly treats the urinary finding as a reason to omit the indicated lumbar puncture. B omits *Listeria* cover required for this age group. D substitutes oral treatment despite the indication for parenteral antibiotics. E provides parenteral treatment but substitutes gentamicin for the third-generation cephalosporin specified by the applicable fever guideline. ([nice.org.uk](https://www.nice.org.uk/guidance/ng143/chapter/recommendations))

Reference: Fever in under 5s: assessment and initial management — recommendations 1.5.3–1.5.7 (26 November 2021) — https://www.nice.org.uk/guidance/ng143/chapter/recommendations Urinary tract infection in under 16s: diagnosis and management — recommendations 1.1.3 and 1.2.2–1.2.3 (27 July 2022) — https://www.nice.org.uk/guidance/ng224/chapter/Recommendations