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Proteus CAUTI — SCE Infectious Diseases MCQ

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EasyHealthcare-Associated InfectionsProteus CAUTISCE Infectious Diseases

A 58-year-old man with a long-term urinary catheter develops catheter-associated urinary tract infection (CAUTI) with Proteus mirabilis. He has recurrent encrustation and catheter blockage. What biochemical property of Proteus explains the catheter encrustation?

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Correct answer: E — Urease production — Proteus hydrolyses urea to ammonia, raising urinary pH and causing struvite crystal precipitation on the catheter

Proteus mirabilis is a urease-producing organism. Urease converts urea to ammonia and carbon dioxide, alkalinising the urine (pH >7). The alkaline environment causes crystallisation of magnesium ammonium phosphate (struvite) and calcium phosphate on the catheter surface, leading to encrustation and blockage. Management includes catheter change, appropriate antibiotics (guided by sensitivities — Proteus is inherently resistant to Nitrofurantoin), catheter maintenance solutions, and ensuring adequate hydration.

Reference: NICE NG113 2018 – CAUTI; BNF 2024 – Proteus UTI