Increased gut permeability and bacterial translocation in Pseudomonas pneumonia-induced sepsis

Objective: Gut injury and barrier dysfunction may contribute to the pathogenesis of sepsis and multiple organ dysfunction syndrome. The objective of this study was to determine whether gut injury could be demonstrated in hyperdynamic, normotensive sepsis induced by Pseudomonas pneumonia. Design: Randomized animal study. Setting: University laboratory. Subjects: Adult male Sprague-Dawley rats. Interventions.. Sepsis was induced by intratracheal instillation of Pseudomonas aeruginosa. Measurements and Main Results: We measured gut mucosal and microvascular injury. in the first experiment, gut mucosal permeability was measured by Cr-51-EDTA uptake in control (n = 6), pneumonia 20-hr (n = 4), and pneumonia 40-hr (n = 4) groups. In the second experiment, microvascular permeability was measured by albumin extravasation, and morphologic abnormalities were scored in control (n = 6), pneumonia 20-hr (n = 9), and pneumonia 40-hr (n = 11) groups. Bacterial translocation to mesenteric lymph nodes was determined in both experiments. Cardiac index increased significantly in the pneumonia compared with control rats (64 +/- 2.1, 68 +/- 1.3, vs. 46 +/- 2 mL/min/100 g, p < .05; all results are listed in the order of pneumonia 20-hr, pneumonia 40-hr, and control groups as mean +/- SEM). Mean blood pressure was normal and was not different between groups (112 +/- 3, 111 +/- 2, vs. 118 +/- 2 mm Hg). Cr-51-EDTA recovery in urine 6 hrs after gavage increased significantly in both pneumonia groups vs. controls (17.5 +/- 2.2%, 17.9 +/- 7%, vs. 4 +/- 0.7%; p < .05). Albumin leak (tissue/plasma ratio) increased significantly in the middle and distal small intestine in the pneumonia 40-hr group vs, controls (0.68 +/- 0.05, 0.76 +/- 0.07, vs, 0.45 +/- 0.04, p < .05 in the middle small gut; 0.75 +/- 0.09, 0.85 +/- 0.07, vs. 0.51 +/- 0.05, p < .05 in the distal small gut). Bacterial translocation to mesenteric lymph nodes increased significantly in pneumonia 40-hr rats vs. controls (positive culture 67% vs. 8%; p < .05). Conclusions: This study demonstrates gut mucosal and microvascular injury and gut barrier dysfunction in normotensive sepsis secondary to bacterial pneumonia. The mechanism and significance of the injury need to be determined.