Translocation of Enterococcus in jaundiced and anergic rats

Abstract

Abstract Background Translocation of bacteria from the gut to other organs is one cause of systemic complications in obstructive jaundice. Furthermore, hyperbilirubinaemia appears to cause anergy. This study investigated whether these responses (translocation of gut bacteria and anergy) increase the postoperative mortality rate in rats in which obstructive jaundice is induced surgically by ligature of the bile duct. Methods Some 88 male Wistar rats were divided into six groups. All rats except those in group 1 received gentamicin by the oral route (0·7 mg in 1 ml water, daily for 6 days) to ensure intestinal decontamination. On day 7, all rats except those in groups 1 and 2, which had vehicle only, received Enterococcus. Statistical analysis was by Student's test and Fishers's exact test. All animals underwent standard blood testing, delayed hypersensitivity tests, haematimetry and serum endotoxin determinations. Flow cytometry was used to count CD3-, CD4- and CD8-positive lymphocytes. On the day 5 after surgery, these assays were repeated and, in addition, the rats were killed for microbiological analysis of gut and viscera contents (liver, spleen, mesentery and lung). Results Five days after surgery, mean bilirubin levels in groups 5 and 6 were greater than 14 mg dl−1. In addition, all rats in groups 5 and 6 showed absence of the delayed hypersensitivity response, indicating anergy. Lymphocyte counts in each group are shown in the Table. The mean proportion of CD8-positive lymphocytes in rats that had received Enterococcus (groups 3–6) was 16 per cent compared with 25 per cent in groups 1 and 2 (P < 0·05). The mean percentage of CD3-positive lymphocytes in groups 5 and 6 was 51 per cent, but 71 per cent in all other groups (P < 0·05). Likewise, the mean percentage of CD4-positive lymphocytes in groups 5 and 6 was 32 per cent, but 47 per cent in all other groups (P < 0·05). The postoperative mortality rate in group 4 (17 per cent) was significantly lower than that in the obstructive jaundice groups 5 and 6 (62 per cent) (P < 0·01). Post-mortem microbiological analyses revealed translocation of Enterococcus only in groups 5 (80 per cent) and 6 (70 per cent). Enterococci were most frequently present in the mesentery (80 and 70 per cent respectively), followed by the liver (40 and 40 per cent), spleen (20 and 20 per cent) and lungs (10 and 10 per cent). Conclusion (1) Obstructive jaundice in rats leads to immunological alterations including anergy. (2) Obstructive jaundice in rats favours translocation of enterococci from the gut to other organs. (3) The postoperative mortality rate in jaundiced rats was much higher than that in sham-operated rats.