Total parenteral nutrition, bacterial translocation, and host immune function

Total parenteral nutrition (TPN) is associated with increased infectious complications in trauma and perioperative patients compared with enteral nutrition support. This study evaluated the effects of TPN on splenocyte and peritoneal macrophage (PMØ) function and intestinal bacterial translocation. Male Wistar rats underwent central vein cannulation and were randomized to isocaloric feeding of a regular chow diet (RD) plus saline infusion or TPN for 7 days. Splenocytes and PMØ were harvested to assess concanavalin A mitogenesis, superoxide production, and Candida albicans phagocytosis. Bacteria-positive mesenteric lymph nodes (MLNs) were found in 77% (10 of 13) of TPN-fed rats compared with 17% (2 of 12) of RD-fed rats (p < 0.05). Splenocyte mitogenesis, PMØ superoxide production, and C. albicans phagocytosis were significantly decreased in the TPN group compared with results in the RD group. In a second study, rats received RD, TPN, and parenteral nutrition (PN) with 10% or 20% of calories given as oral chow (PN and 10% chow and PN and 20% chow) for 7 days. PN and 10% chow reversed the TPN-induced suppression of C. albicans phagocytosis. PN + 20% chow significantly increased splenocyte mitogenesis, PMØ superoxide production, and C. albicans phagocytosis and killing to normal levels and was associated with a decreased incidence of bacteria-positive MLN. Thus, administration of TPN is associated with impaired PMØ microbicidal and splenocyte proliferative function. These defective cellular functions were reversed with a small amount of oral feeding.