The optimal timing, dosing, and duration of a prophylactic antibiotic regimen for PCNL procedures has also been a point of discussion. The AUA best practice policy statement currently recommends that a one-time dose on the day of the procedure is sufficient. The EAU guidelines are less definitive in concluding that a short course is adequate but that the "length of time is to be determined." Mariappan and colleagues in a prospective non-randomised trial found that 52 patients who had dilated collecting systems, stone burden greater than 2 cm, and no confounding factors predisposing to UTIs who received a 1-week course of ciprofloxacin before PCNL had a 3-fold lower risk of postoperative UTI and SIRS than 46 patients who received standard perioperative antibiotics on the day of surgery.