Infectious stones are formed when pathogenic bacteria infect the urinary tract and secrete urease to break down the urea in the urine, which forms stones after a series of chemical reactions. The main components of infected stones are magnesium ammonium phosphate and carbonate apatite. There are many pathogenic bacteria capable of secreting urease, including Aspergillus, Pneumocystis, Pseudomonas aeruginosa, Escherichia coli and Mycoplasma urealyticum, and the most common one is Mycoplasma chimaerae. The pathogenic bacteria infect the urinary tract and secrete urease, which breaks down urea into ammonia and carbon dioxide. Ammonia combines with water to form ammonium salts, which combine with magnesium and phosphate in the urine to form magnesium ammonium phosphate. Carbon dioxide combines with water to form bicarbonate, making the urine alkaline. Calcium ions, phosphate and carbon dioxide in the urine combine in an alkaline environment to form carbonate apatite. Infected stones grow faster and often fill the kidney ducts, forming cast stones. Stones blocking the ducts, combined with infection, tend to impair kidney function and therefore require aggressive treatment, usually requiring surgical removal of the stones. Residual stones and infection after surgery cause stones to recur quickly and form cast stones again. Therefore, stones should be removed as much as possible during surgery, and postoperative aggressive control of urinary tract infection and acidified urine is needed to prevent stone recurrence and excessive growth.