Bacterial Translocation in Experimental Shock Is Dependent on the Strains in the Intestinal Flora

Abstract

Background: Enteric microorganisms are responsible for a significant proportion of post-surgical infections. Intestinal mucosal injury may permit translocation of bacteria and endotoxin. This study investigates translocation in peritonitis and ischemia/reperfusion by inoculating different bacterial species into the small intestine. Methods: Twenty-five pigs were monitored hemodynamically and divided into three groups: controls (C), ischemia/reperfusion (I/R), and peritonitis (P). Intramucosal pH (pHi) was calculated tonometrically. A perfusion tube was positioned in the ileum for inoculation of the bacterial strains. In a first study period a non-pathogenic bacterium was used, whereas Escherichia coli strains with known ability to translocate were used in a second. Blood and mesenteric lymph nodes (MLNs) were obtained for bacterial culture and endotoxin analyses. Results: Mesenteric arterial blood flow and pHi decreased in groups I/R and P. Endotoxin levels increased in these groups in period 1, whereas in period 2 an increase over time was only observed in group P. No bacterial translocation to blood or MLNs occurred in period 1. In period 2 bacteria translocated to MLNs in all animals, including controls. Translocation to central and/or mesenteric venous blood was found in all groups, but mainly in I/R and P. The incidence of mucosal injury was similar in the two periods. Conclusions: Since positive blood and MLN samples were only found in period 2, we conclude that translocation of bacteria seems to be more dependent on the presence of translocating strains in the intestinal bacterial flora than on the mucosal insult.