What type of calculi are typically formed in alkaline urine due to Proteus vulgaris?

Struvite stones, also known as magnesium ammonium phosphate stones, are typically formed in alkaline urine conditions, which are often a result of urinary tract infections (UTIs) caused by urease-producing organisms like Proteus vulgaris. These bacteria hydrolyze urea to ammonia, increasing the pH of the urine and creating a favorable environment for the precipitation of struvite crystals.

In alkaline urine, the ammonium ions combine with phosphate and magnesium to form struvite stones, leading to a characteristic association between these calculi and infections by Proteus species. These stones can grow rapidly and may lead to the formation of staghorn calculi, which can obstruct the urinary tract.

Calcium oxalate stones, uric acid stones, and cystine stones have different formation mechanisms and are typically associated with other urinary conditions, not specifically linked to the alkaline urine environment induced by Proteus vulgaris. Hence, struvite stones are the direct consequence of such infections and alkaline conditions in the urine.