Bacterial translocation in a large-animal model of small-bowel transplantation: Portal vs systemic venous drainage and the effect of tacrolimus immunosuppression

Objective: To study whether bacterial translocation is more prevalent after small-bowel transplantation with systemic venous drainage (SVD) vs portal venous drainage (PVD) and whether it is influenced by immunosuppression. Design: We performed 15 small-bowel transplantations in pigs. Group 1 (n=5) had SVD and no immunosuppression; group 2 (n=6), PVD and no immunosuppression; and group 3 (n=4), PVD and immunosuppression with tacrolimus and methylprednisolone sodium succinate. Portal and systemic blood, portal and mesenteric lymph nodes, and liver were cultured in donors and recipients on postoperative day 0 (POD 0) and in recipients on postoperative day 3 (POD 3). Jejunal and ileal contents were also sampled at these times. Subjects: Outbred male Yorkshire-Landrace pigs. Main Outcome Measures: (1) Blood and tissue bacterial cultures, (2) blood endotoxin levels, and (3) histopathologic examination. Results: Cultures were positive for bacteria in 32% (16/50) of samples on POD 0 and 88% (22/25) on POD 3 in group 1, in 18% (11/60) of samples on POD 0 and 97% (29/30) on POD 3 in group 2, and in 8% (3/40) of samples on POD 0 and 95% (19/20) on POD 3 in group 3. Systemic blood cultures were positive for bacteria on POD 3 in 60% (3/5) of pigs in group 1, 83% (5/6) in group 2, and 100% (4/4) in group 3. Significantly more bacteria were present in the ileum than in the jejunum on POD 0 in group 2; this difference approached significance in groups 1 and 3. Bacterial numbers were identical in the ileum and jejunum by POD 3 in all groups. Circulating endotoxin levels were significantly elevated on POD 3 vs POD 0 only in group 1. Endotoxin levels were not significantly different between the SVD group (group 1) and either PVD group (groups 2 and 3). Conclusions: Bacterial translocation is prevalent after small-bowel transplantation in pigs whether PVD or SVD is used. Immunosuppression with tacrolimus does not prevent bacterial translocation but may reduce systemic endotoxemia.