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How do kidney stones raise the risk of urinary tract infection?

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The most common cause of urinary tract infection is invasion into the urethra of Escherichia coli, a type of bacterium that normally inhabits the bowel. — urinary tract infection The most common cause of urinary tract infection is invasion into the urethra of *Escherichia coli*, a type of bacterium that normally inhabits the bowel.

Kidney stones increase the risk of a urinary tract infection (UTI) primarily by causing urinary tract obstruction, which disrupts the normal flow of urine. When urine flow is obstructed, bacteria are more likely to ascend the urinary tract, leading to persistent and intractable infections within the renal pelvis and kidney tissue.123

Furthermore, kidney stones themselves can act as a site for bacterial colonization. A clump of bacteria, degenerated tissue, or other debris can serve as a nucleus for the precipitation of urinary salts, around which a stone forms and grows. Because these stones can harbor bacteria and block the flushing action of urine, infections are often difficult to eradicate with antibiotics alone until the obstruction is physically removed or relieved.132