Which organism is commonly associated with urinary tract infections in children and is urease positive?

• A. Escherichia coli
• B. Proteus mirabilis
• C. Klebsiella pneumoniae
• D. Pseudomonas aeruginosa

Answer: (B)

Urease production by bacteria converts urea into ammonia, which raises the urine pH. This alkaline environment promotes the formation of certain stones and helps some bacteria persist in the urinary tract. Proteus mirabilis is the classic urease-positive organism associated with urinary tract infections in children. Its urease activity rapidly alkalinizes urine, leading to the precipitation of magnesium ammonium phosphate (struvite) stones and enabling robust infection, sometimes with catheter use or anatomical abnormalities. While Escherichia coli is the most common UTI pathogen overall, it is not urease-positive; Klebsiella can be urease-positive but is not as strongly linked to stone formation, and Pseudomonas is not the archetypal urease-driven UTI agent.