Administering prophylactic antibiotics up to two hours before cardiac surgery may significantly decrease surgical site infection (SSI) rates, according to a study published in the January issue of Infection Control and Hospital Epidemiology.

Researchers led by Renato Finkelstein, MD, of the Israel Institute of Technology in Haifa tracked SSIs over a 10-year period among patients who underwent cardiac surgery. There were a number of infection control interventions among the 2,367 surgeries in the analysis, including hair removal using cream, covering the sternotomy area with iodine, cleaning areas using povidone-iodine preparations  and starting antibiotic prophylaxis up to two hours before the first incision.

During the first three years of the research, patients received either vancomycin or cefazolin as part of a randomized, controlled study. Afterward, patients received cefazolin adjusted for weight or vancomycin if allergic to cefazolin. During these last four years, administration of the antibiotic began between 30 and 120 minutes before the first incision and recommendations were to discontinue after 24 hours. Patients receiving cefazolin received an additional dose during surgery if the procedure lasted more than four hours.

Overall, 8.4 percent of patients developed SSIs. During the last four years of the study, SSI rates declined by more than 50 percent. Infection rates did not differ significantly between the two drugs. Infections developed in 8.1 percent of patients who received antibiotics within the two-hour time frame compared with 13.9 percent of patients who received antibiotics at different times. Further analysis found emergency surgery, age, two specific surgeons and administration of prophylactic antibiotics outside the two-hour time frame to be predictors of superficial infection.

The authors noted their findings were consistent with previous research that found an association between timing of antibiotic prophylaxis and SSIs.

“Infection control programs can help surgeons by identifying specific remediable risk factors for postsurgical infection in specific populations,” they argued.