RESUMEN
A cohort study was carried out at the Marilia Medical School Hospital. In the first phase the pattern of antibiotic use was evaluated. Antibiotics were prescribed for 55.4 percent of the patients; antibiotic combinations were used in 43 percent. Therapeutic use of antibiotics was considered inadequate in 27 percent. Respiratory and skin infections were the most frequently diagnosed. In up to 31 percent of the cases the treatment of respiratory infections was considered inadequate. The surgical use of antibiotic prophylaxis was evaluated in the second phase. Prophylaxis was indicated in 73.2 percent of the surgeries. The antibiotics most used for prophylaxis were first generation cephalosporins. In 78.9 percent of the surgeries, the antibiotic was correctly chosen. In 15.9 percent of the surgeries, the initial antibiotic administration was correctly timed. The use of antibiotics in the post-operative period was appropriate in 29.8 percent of the cases. The independent risk factors for surgical site infection (SSI), as determined by logistic regression analysis adjusted to class of wound risk, were the choice of antibiotic to be used prophylactically and the duration of antibiotic treatment in the post-operative period. Those who received appropriate prophylactic antibiotics had a lower rate of SSI than those who received innapropriated antibiotics [RR=0.49/95 percent; CI=0.25-0.90]. Patients who received prophylactic antibiotics correctly in the post-operative period had a lower risk of SSI than those who did not [RR=0.21/95 percent; CI=0.70-0.63]. The mean length of hospital stay was shorter among patients whose prophylactic treatment was correctly employed than among for which it was not [6.1 (±9.8) and 11.1 (±13.5) days, p=0.25].