Effects of enteral and intravenous antimicrobial treatment on survival following intestinal ischemia in rats.

One hundred and twenty rats underwent transection of the superior mesenteric artery. The animals were randomly divided into eight groups of 15 animals. Control group 1 and groups 3, 5, and 7 received intravenous normal saline, gentamicin, metronidazole, and gentamicin plus metronidazole, respectively. Control group 2 and groups 4, 6, and 8 received the same compounds enterally. Small and large bowel sections were taken postmortem and a necrosis score was assigned in blinded fashion. Gentamicin did not prolong survival, indicating that gram-negative microbes were not important in this pathology. Longer survival times for animals given either metronidazole or gentamicin plus metronidazole (P less than 0.01) indicate that anaerobes were a causative factor in mortality. During the first 15 hr after ischemia, antibiotics did not change mortality. After 15 hr, enteral administration was superior to intravenous administration in any regimen including metronidazole (P less than 0.01).