## **Core Concept**
The question pertains to the types of urinary tract stones associated with infections. Urinary tract infections (UTIs) can lead to the formation of specific types of stones due to the presence of certain bacteria that alter the urine's chemical composition.

## **Why the Correct Answer is Right**
The correct answer, **struvite stone**, is associated with UTIs because certain bacteria, such as *Proteus*, *Pseudomonas*, and *Klebsiella*, produce the enzyme urease. This enzyme breaks down urea into ammonia and carbon dioxide, increasing the urine's pH. An alkaline environment promotes the formation of struvite stones, which are composed of magnesium ammonium phosphate.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Calcium oxalate stones are the most common type of urinary stone but are not directly caused by UTIs. They are more related to diet, dehydration, and genetic predisposition.
- **Option B:** Uric acid stones form in acidic urine and are associated with conditions like gout, chemotherapy, and certain gastrointestinal diseases, not directly with UTIs.
- **Option D:** Cystine stones are rare and occur in patients with cystinuria, a genetic disorder affecting amino acid transport in the kidneys and intestines. They are not directly associated with UTIs.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that struvite stones are often associated with UTIs caused by urease-producing bacteria. These stones can grow rapidly and become staghorn calculi, which are large stones that fill the renal pelvis and can cause recurrent infections.

## **Correct Answer:** . Struvite stone