Which type of bacteria is primarily associated with the formation of struvite stones?

Struvite stones, also known as infection stones, are primarily associated with urinary tract infections caused by certain types of bacteria that possess the ability to produce urease. Urease is an enzyme that hydrolyzes urea to ammonia, which increases the pH of urine and promotes the formation of struvite crystals (magnesium ammonium phosphate).

Proteus species, particularly Proteus mirabilis, are well-known for their urease activity and are a common cause of urinary tract infections that can lead to the formation of struvite stones. Klebsiella species also have some urease activity and can contribute to this condition, further supporting the association between these bacteria and struvite stone formation.

In summary, the correct choice reflects the involvement of Proteus and Klebsiella in the development of struvite stones due to their urease production, leading to significant changes in urine chemistry that favor stone formation.