BACTERIAL WOUND COLONIZATION AFTER BROAD-SPECTRUM VERSUS NARROW-SPECTRUM ANTIBIOTICS

Broad-spectrum versus narrow-spectrum antibiotic prophylaxis for patie nts who undergo cardiac operations is variously advocated to reduce th e incidence of all infections or, conversely, to prevent resistant sup erinfections. Previous studies of prophylaxis have shown a reduction i n the incidence of staphylococcal infections with some increased resis tance. We studied preoperative and postoperative wound colonization as a surrogate for infection. Among 78 patients undergoing cardiac proce dures, the type of prophylaxis was allocated as follows: narrow-spectr um (nafcillin), 24 patients; midspectrum (cephapirin), 26 patients; an d broad-spectrum (ceftriaxone), 28 patients. Seventeen patients who un derwent other procedures received no antibiotics and served as control s. Cultures of the operative site were done preoperatively, and 3 and 6 days postoperatively. The incidence of preoperative skin colonizatio n with staphylococci was identical (95%) in all groups. Postoperativel y, more patients receiving nafcillin (48%) were culture-negative for a ll organisms than were either of the other groups receiving antibiotic s (27% and 22%) (p < 0.05). Gramnegative bacilli were infrequent colon izers and neither did the incidence of infection with these organisms increase nor did resistance develop in any group. The infection rates were not different among the treatment groups. Thus, a narrow-spectrum antistaphylococcal penicillin may offer an advantage in terms of both prophylaxis for cardiac operations and hospital costs.