Which type of kidney stone is associated with urease-positive organisms?

Struvite stones, also known as magnesium ammonium phosphate stones, are specifically associated with urease-positive organisms. These bacteria, such as Proteus species, Klebsiella, and some strains of Staphylococcus, have the capability to produce urease, an enzyme that hydrolyzes urea to ammonia. This process raises the pH of urine, leading to an alkaline environment.

In an alkaline urinary environment, ammonia combines with phosphate to form struvite stones, which are typically larger and can even create staghorn calculi that fill the renal pelvis due to their size. The presence of urease-positive bacteria is a crucial factor in the formation of these stones, as they not only increase the urine's pH but also contribute to the precipitation of the minerals that comprise struvite stones.

Other types of kidney stones, such as uric acid, calcium, and cystine stones, do not have this specific association with urease-positive organisms. Uric acid stones are linked to high levels of uric acid in urine and are influenced by factors such as low urine volume and high protein intake. Calcium stones, the most common type, are primarily associated with conditions that lead to hypercalcemia or hypercalciuria.