Which type of kidney stone is most commonly associated with infection and formed in the setting of urease-producing bacteria?

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Multiple Choice

Which type of kidney stone is most commonly associated with infection and formed in the setting of urease-producing bacteria?

Infection-related stones form when bacteria that produce urease raise the urine pH. Urease splits urea into ammonia and carbon dioxide, making the urine more alkaline. In this alkaline environment, magnesium, ammonium, and phosphate readily precipitate as magnesium ammonium phosphate, the component of struvite stones. These stones are classicly associated with urease-positive organisms such as Proteus and can grow quickly into large, branching “staghorn” calculi that fill parts of the kidney and harbor bacteria, perpetuating infection if not treated. Struvite stones are usually visible on a regular X-ray because of their phosphate content, aiding diagnosis. Treatment involves eliminating the infection with antibiotics and removing the stone, with steps to prevent recurrence by controlling the infection and urine pH. Other stones—calcium oxalate, uric acid, and cystine—are not driven primarily by infection with urease-producing bacteria or by alkaline urine, so they fit less well with the scenario described.

Infection-related stones form when bacteria that produce urease raise the urine pH. Urease splits urea into ammonia and carbon dioxide, making the urine more alkaline. In this alkaline environment, magnesium, ammonium, and phosphate readily precipitate as magnesium ammonium phosphate, the component of struvite stones. These stones are classicly associated with urease-positive organisms such as Proteus and can grow quickly into large, branching “staghorn” calculi that fill parts of the kidney and harbor bacteria, perpetuating infection if not treated.

Struvite stones are usually visible on a regular X-ray because of their phosphate content, aiding diagnosis. Treatment involves eliminating the infection with antibiotics and removing the stone, with steps to prevent recurrence by controlling the infection and urine pH.

Other stones—calcium oxalate, uric acid, and cystine—are not driven primarily by infection with urease-producing bacteria or by alkaline urine, so they fit less well with the scenario described.

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