OBJECTIVE: The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has made a strong impact on the strategy of peri-operative antibiotic prophylaxis, since MRSA has become one of the most common causative organisms of nosocomial infection in recent years. In this study, we conducted a bacteriological evaluation of surgical drains before and after introducing strategies to decrease MRSA infection rates. DESIGN AND PATIENTS: Between January 1987 and December 1994, we performed a total of 2, 755 surgical operations on inpatients, including 1,635 major and 1, 120 minor operations. Almost all surgical drains were examined bacteriologically when they were removed. The number of drains examined was 460 +/- 47 (mean +/- SEM) per year. Since the increased incidence of MRSA infection, we started exclusively using a closed drainage system and first-generation cephalosporins in 1991. The strategy was evaluated by comparing the positive rates of drain cultures, changes in bacteriological features, and incidence of MRSA infection for the 4-year periods before and after 1991. RESULTS: The positive rate of bacteria in the drains decreased significantly (p < 0.01) from 25 +/- 2 to 16 +/- 1%. Bacteriologically, the positive rate of Staphylococcus spp. decreased significantly (p < 0.05) from 7 +/- 2 to 3 +/- 0.3%. Positive rates of MRSA decreased significantly (p < 0.05) from 2.1 +/- 0.3 to 1.3 +/- 0.3%. Streptococcus declined dramatically from 3.0 +/- 0.3 to 0.3 +/- 0.1%. Of gram-negative strains, Pseudomonas and Escherichia coli were most often isolated. They showed no significant difference in positive rates between the terms. CONCLUSION: A closed drainage system and thorough use of the first-generation cephalosporins for prophylaxis were effective in decreasing positive bacterial culture of drains and reducing the incidence of MRSA on drains after surgery.