Irrigation of the peritoneal cavity and local antibiotics in the treatment of peritonitis.

Peritonitis was induced in the Sprague-Dawley rats by the implantation of gelatin capsules containing 0.3 milliliter of human fecal suspension into the peritoneal cavity. The rats were then treated with systemic antibiotics or peritoneal irrigation with normal saline solution alone or cephalotin solution, 2,000 micrograms per liter, or both. The results show that peritoneal irrigation with normal saline solution or with cephalotin alone was ineffective, even though the cephalotin concentration used inhibited the growth of all bacterial species isolated during the free stage of peritonitis in vitro. Systemic antibiotics alone as well as in combination with peritoneal irrigation significantly improved the survival rate, p less than or equal to 0.05 and p less than or equal to 0.02, respectively. However, only systemic antibiotics in combination with peritoneal irrigation resulted in a significant cure rate compared with the control group and the group treated with systemic antibiotics alone, p less than or equal to 0.002. There was no increase in the cure or survival rates when antibiotics were added to the peritoneal irrigation fluid. In the second experiment, seven of ten rats treated with systemic antibiotics survived, but only two rats had no intraperitoneal abscesses at autopsy. Intraperitoneal application of antibiotics did not improve these results: six rats survived, and one rat was cured. We conclude that peritoneal irrigation alone is ineffective in the treatment of peritonitis. The addition of peritoneal irrigation to systemic antibiotic therapy, however, resulted in a significantly increased cure rate. The addition of antibiotics to the irrigant does not further improve the results, and local antibiotics are not more effective than systemic antibiotics. We believe that benefit of peritoneal irrigation is due to its mechanical effect.