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

J. P. Fryer, S. Kim, C. L. Wells, C. Fasola, R. P. Jechorek, D. L. Dunn, J. Pirenne, L. Arazola and R. W. Gruessner
Department of Surgery, University of Minnesota, Minneapolis, USA.

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.