While often overused, antibiotics can be underused, too, particularly before a major operation. Infectious-disease experts have long recommended giving patients a preventive antibiotic during the 60 minutes before the initial incision, to reduce the risk of potentially deadly infections. A preoperative antibiotic achieves adequate blood levels at the time of surgery, thus preventing a postoperative infection. But surgeons followed that advice in only about half of cases, according to a study in the February issue of Archives of Surgery, involving more than 34,000 patients. If you’re about to go under the knife, make sure you receive a timely dose of an antibiotic.