Because postsurgical wound infection is a major source of morbidity and expense, prophylactic antibiotics are frequently given. Current guidelines for their administration are nonspecific but recommend use of antibiotics in surgeries with a high risk of infection or when an infection could have serious consequences. While generally safe, prophylactic antibiotics are associated with allergic reactions, side effects, and the potential for bacterial resistance and superinfection. Knight and colleagues studied wound infection in cases of clean general surgery to establish guidelines for prophylactic antibiotic use in such surgeries.

The authors studied all of the 1,223 clean surgeries conducted in a city hospital during a one-year period. Based on the National Nosocomial Infection Surveillance (NNIS) classification system, 69 percent of cases had no risk, 28 percent were NNIS class 1, and 3 percent were class 2. Wound infections were documented in 16 (1 percent) of the patients. The infection rates by NNIS classification were 0.59 percent in patients in class 0, 2.6 percent in patients in class 1, and 5.4 percent in patients in class 2. Nearly one half of the NNIS class 0 group received prophylactic antibiotics. The infection rate in these 427 patients was 0.94 percent, compared with 0.2 percent in the 414 patients in the class 0 group who did not receive antibiotics. Similarly, infection rates were 2.44 percent in NNIS class 1 patients who received antibiotics and 3.03 percent in those who did not. In NNIS class 2 patients, 6.7 percent of those receiving antibiotics developed infections, but no infections were recorded in patients who did not receive antibiotics.

The authors conclude that prophylactic antibiotics do not reduce the rate of wound infections in clean surgical cases, and they do not recommend using them in NNIS class 0 or class 1 cases.