The effect of one prophylactic dosage of antibiotics on experimentally induced lethal intraabdominal sepsis.

In order to study the effect of one preoperative dosage of antibiotic on the mortality rate, incidence of abscesses, adhesions and intraperitoneal fluid, a previously described reproducible experimental model of intraabdominal infections in rats has been used. Preoperatively, the rats were fed with lean ground beef for two weeks in order to change the intestinal microflora into a microflora similar to humans. The antibiotics tested were: doxycycline (1 mg), cefoxitin (40 mg), tinidazole (8 mg) + netilmicin (5 mg), clindamycin (150 mg) + netilmicin (5 mg) and trimethoprimsulfa (76.8 mg) + tinidazole (8 mg). The results indicate that one preoperative dosage of the antibiotic(s) significantly reduces the mortality rate in rats with intraabdominal sepsis. Intraperitoneal fluid was observed in all non-surviving rats, whereas in the surviving animals no fluid was present regardless of the type of antibiotic. The rate of intraabdominal abscesses was significantly higher in the doxycycline group compared with the other treated groups, indicating an inadequate anaerobic cover of doxycycline. The incidence of intraabdominal postoperative adhesions was similar in all groups except the trimethoprimsulfa + tinidazole group, which had a significantly lower number of rats with adhesions.