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Acute pyelonephritis — MSRA MCQ

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HardUrinary Tract InfectionsAcute pyelonephritisMSRA

A 34-year-old non-pregnant woman presents with 24 hours of dysuria, urinary frequency, fever and right loin pain. She has no vaginal symptoms, vomiting, rigors or visible haematuria. Her temperature is 38.2°C, pulse 96 beats/minute, blood pressure 118/72 mmHg and respiratory rate 16 breaths/minute. She is alert, drinking normally and can take oral medication. There is right costovertebral-angle tenderness. A midstream urine sample has been obtained before treatment. She has no drug allergies, her eGFR is 84 mL/minute/1.73 m², and she has no known urinary tract abnormality, diabetes or immunosuppression. A urine culture 5 months ago grew Escherichia coli susceptible to cefalexin and co-amoxiclav but resistant to trimethoprim. She has not received antibiotics since. What is the most appropriate immediate antimicrobial management?

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Correct answer: C — Start cefalexin 500 mg orally three times daily for 7 days

This presentation is acute pyelonephritis rather than lower UTI: fever and costovertebral-angle tenderness indicate upper urinary tract involvement. She is haemodynamically stable, hydrated, not vomiting and able to take oral treatment, so oral rather than intravenous therapy is appropriate. Cefalexin is a NICE first-choice oral antibiotic for acute pyelonephritis for 7–10 days; her previous culture also supports likely susceptibility. Nitrofurantoin is appropriate for uncomplicated lower UTI but should be avoided in pyelonephritis because it does not achieve adequate renal-tissue concentrations. Co-amoxiclav is an oral option only when current culture results demonstrate susceptibility; a culture from 5 months ago is insufficient for empirical co-amoxiclav prescribing. Admission for intravenous cefuroxime would be appropriate if she were unable to take oral medication, clinically deteriorating, septic or otherwise severely unwell. Ciprofloxacin is reserved for when other first-choice antibiotics are unsuitable because of important fluoroquinolone safety restrictions; cefalexin remains suitable here. The current urine culture should be reviewed promptly and treatment narrowed or changed if resistance is identified.

Reference: NICE NG111: Pyelonephritis (acute): antimicrobial prescribing — Recommendations (September 2024) — https://www.nice.org.uk/guidance/ng111/chapter/recommendations NICE NG111: Pyelonephritis (acute): antimicrobial prescribing — Summary of the evidence (2018) — https://www.nice.org.uk/guidance/NG111/chapter/summary-of-the-evidence NICE NG111: Pyelonephritis (acute): antimicrobial prescribing — Summary of the evidence (2018) — https://www.nice.org.uk/guidance/NG111/chapter/summary-of-the-evidence