Objective: We tested whether alterations in intestinal morphology and mucus gel correlate with differences in Salmonella typhimurium translocation between rats treated with total parenteral nutrition (TPN) and rats given a diet of chow.
Methods: Twenty-seven male Wistar rats were assigned to one of two groups: one received TPN for 14 d and the other (control) received standard rat chow and water ad libitum. Salmonella typhimurium (5 x 10(8) cells; GIFU 12142) was injected into a closed ileal loop. Portal venous blood (PVB), inferior vena cava blood (IVCB), and mesenteric lymph nodes (MLNs) were sampled for evaluation of bacterial translocation. Sections of the loop were prepared and stained with hematoxylin and eosin, periodic acid-Schiff (PAS), and fluorescein isothiocyanate-labeled Ulex europaeus agglutinin I (FITC-UEA-I) for image analysis. Perimeter, mucosal thickness, villus area, and positively stained mucus area were measured. A fluorescent antibody study was also done.
Results: Organisms were found in cultures of 1 in 13 control rats and 9 in 14 TPN rats. There were more bacteria in MLNs than in PVB or IVCB. There was no increase in the number of bacteria over time in PVB, IVCB, or MLNs. Perimeter and villus area (P < 0.001) and mucosal thickness (P < 0.01) were significantly smaller in the TPN group than in the control group. The positively stained mucus area was significantly smaller in the TPN group than in the control group (P < 0.05 with PAS, P < 0.01 with FITC-UEA-I). Salmonella typhimurium invaded specifically through Peyer's patches. In all culture-negative samples, bacteria were trapped by the mucous layer, with a very small number attached to the epithelial surface.
Conclusion: Significant villous atrophy and reduction of mucus play an important role in the rapid translocation of S. typhimurium through Peyer's patches in rats after 2 wk of TPN.