## **Core Concept**
The question tests knowledge on the association between urinary tract infections (UTIs) caused by specific bacteria and the type of renal calculi (kidney stones) they are commonly linked with. **Proteus** infections are known to cause UTIs and are associated with the formation of certain types of kidney stones.

## **Why the Correct Answer is Right**
The correct answer, **struvite stones**, is associated with infections caused by **Proteus** bacteria. **Proteus** species, like some other urease-positive bacteria (e.g., *Pseudomonas*, *Klebsiella*, and *Serratia*), can split urea into ammonia and carbon dioxide through the action of the enzyme urease. This reaction increases the pH of the urine, leading to the formation of **struvite stones** (magnesium ammonium phosphate stones). These stones are typically seen in the context of UTIs and are more common in women.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Calcium oxalate stones are the most common type of kidney stone but are not directly associated with **Proteus** infections. They can form due to various factors, including diet, dehydration, and genetic predisposition.
- **Option B:** Cystine stones are associated with cystinuria, a genetic disorder leading to excessive excretion of cystine in the urine. They are not directly linked to **Proteus** infections.
- **Option D:** Uric acid stones can form in acidic urine and are associated with conditions like gout or chemotherapy. They are not specifically linked to **Proteus** infections.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **infection stones** (struvite stones) are often associated with urease-positive bacteria, including **Proteus**. These stones can be large and fill the renal pelvis, forming a "staghorn" calculus, which is a classic radiological finding.

## **Correct Answer:** C. Struvite stones.