Decrease of methicillin resistant Staphylococcus aureus prevalence after introduction of a surgical antibiotic prophylaxis protocol in an Italian hospital.

The use of antimicrobials is an important factor contributing to the emergence of antibiotic resistance. The goal of our study was to evaluate the impact of the introduction of an antibiotic surgical prophylaxis protocol on the prevalence of methicillin resistant Staphylococcus aureus (MRSA) infections in a tertiary care hospital. The protocol of surgical antibiotic prophylaxis was designed by a multidisciplinary team and was implemented in December 2001. Between January 2002 and December 2002, pharmacy, laboratory and active surveillance-records were prospectively reviewed to calculate prevalence rates of defined daily doses (DDD), microorganism isolation and health-care related infections. A progressive decrease from 1.58 to 0.56 of MRSA isolations per 1000 patient-days and from 76.4% to 29.4% MRSA prevalence rate was reported (p<0.001). Monthly prevalence rates of MRSA showed a significant linear correlation with the reduction of the DDD of the 3rd generation cephalosporins (r=0.90; p<0.001). MRSA surgical site and blood stream infections decreased from 78% to 38% and from 89% to 38%, respectively (p=0.017 and p=0.026). In our experience, the reduction of 3rd generation cephalosporin use was an effective strategy to reduce the MRSA infection rate and was associated with the reduction of the overall expenditure for antibiotics in the hospital.