An in-hospital workup of a 78-year-old hypeensive, mildly asthmatic man who is receiving chemotherapy for colon cancer reveals symptomatic gallstones. Preoperative laboratory results are notable for a hematocrit of 24% and urinalysis with 18 to 25 WBCs and gram-negative bacteria. On call to the operating room, the patient receives intravenous penicillin. His abdomen is shaved in the operating room. An open cholecystectomy is performed and, despite a lack of indications, the common bile duct is explored. The wound is closed primarily with a Penrose drain exiting a separate stab wound. On postoperative day 3, the patient develops a wound infection. Which of the following changes in the care of this patient could have decreased the chance of a postoperative wound infection?