The kinetics of peritoneal clearance of Escherichia coli and Bacteroides fragilis and participating defense mechanisms.

In a study using pigs, we delineated the dynamic character and the interplay of defense mechanisms that operate in the peritoneal cavity and their effectiveness against Escherichia coli and Bacteroides fragilis. The bacteria were extensively cleared during the first three hours. The concentration of both organisms in the peritoneal fluid decreased by up to 300,000-fold, and the final concentration was a function of the inoculum given. Clearance efficiency did not differ between a bolus dose and prolonged bacterial administration. Peritoneal absorption was a major eliminating mechanism during the first three hours but was limited to bacterial concentrations exceeding approximately 10(9) colony-forming units per milliliter of peritoneal fluid. Intraperitoneal elimination started immediately and continued for approximately six hours. Thereafter, residual bacteria were not eliminated, even though the defense capacity was intact. Prolonged bacterial administration, however, protracted the period for active bacterial destruction.