The use of prolonged courses of prophylactic antibiotics in the intensive care unit may have both financial and health costs. Namias and associates evaluated the use of prophylactic antibiotic therapy in a surgical intensive care unit during a one-year period.

Over 60 percent of all patients (346 of 572) received prophylactic antibiotic therapy for more than one day. Nontransplant patients were less likely to receive prophylactic antibiotics (47 percent, or 151 of 325 patients). A variety of agents were used, with ampicillin/sulbactam being the most commonly prescribed antibiotic for all patients and cefazolin the most common agent for nontransplant patients.

Transplant patients who received more than four days of antibiotic therapy were more likely to have had clean-contaminated surgery than clean surgery and were less likely to have malignant disease. In the nontransplant patients, these distinctions did not occur. Bacteremia and line infection were more frequent in all patients receiving more than four days of prophylactic antibiotics.

The use of prophylactic antibiotics in clean cases is widespread. Their use should be limited to one preoperative dose plus, optionally, two or three postoperative doses, not to exceed 24 hours of treatment. Delays in termination of prophylactic antibiotics were often related to determinations made by physicians from the primary service. Previous studies have demonstrated that limiting the course of perioperative antibiotics could save 18 to 50 percent of associated costs. The occurrence of more line infections and bacteremias in patients receiving more than four days of prophylactic antibiotic therapy may be associated with an increased susceptibility to infection caused by suppression of endogenous flora and selection of pathogens or with some other predisposition to infection. Data were not complete enough to evaluate the second possibility, although there was no difference in patient age, degree of contamination of operation or frequency of malignancy.

The authors conclude that there is poor compliance with the principle of stopping prophylactic antibiotics at 24 hours in the intensive care unit. Prolonged prophylaxis may result in more bacteremias and line infections, as well as increased financial costs.