[Prospective randomized study on effect of duration of antimicrobial prophylaxis for mastectomy]

A prospective randomized trial was done to study effects of the duration of ofloxacin (OFLX) administration for prophylaxis against mastectomy wound infections. One hundred and seventeen women who were hospitalized, during periods between June 1990 and September 1992 were considered for enrollment in this study. Selected patients were treated with 600 mg of OFLX daily in 3 divided doses starting the day before surgery. One group was treated for 5 days and the other was treated for 10 days. A hundred and ten patients were found eligible to complete the study and 58 patients were assigned to the 5-day group and 52 patients were assigned to the 10-day group by the random-envelope method. Nine episodes of infections occurred among the patients in the 5-day group and 12 episodes of infections occurred among those in the 10-day group. The mean time until onset of infection was not significantly different between the 2 groups (12 versus 8 days). The number of strains isolated from the drainage tube when removed was highly correlated with occurrences of infections, and the number of strains isolated from infected wounds was also highly correlated with the need to use a different antibiotic. By multiple regression analysis, age was the only significant factor identified for wound infection. The duration of OFLX administration had no significant effect on the development of wound infections. Prolonged prophylactic use of this drug for mastectomy did not reduce the incidence of postoperative infections in this study.