Gut bacterial translocation/dissemination explains the increased mortality produced by parenteral nutrition following methotrexate.

Mortality is reported to be higher in methotrexate (MTX)-treated animals receiving total parenteral nutrition (TPN), compared to animals receiving enteral nutrition. The increased mortality is felt to be related to gut atrophy and bacterial translocation. In this study, we examined the effect of MTX (30 mg/kg) on survival, body weight loss, gut mass, and gut bacterial translocation in rats randomized to TPN or enteral nutrition. Twenty-four male Sprague-Dawley rats (n = 8 per group) were randomized to TPN, a peptide-based enteral diet (PEP), or CHOW. Animals were weighed daily and followed for survival (6 days). A separate group of rats (n = 6 per group) were similarly randomized and sacrificed at 3 days. Mesenteric lymph node complex, liver, spleen, lung, and blood were cultured for translocating bacteria. Body weight loss was similar in all groups (12.0-16.9 g/day). Mortality was significantly (P < 0.05) higher in the TPN animals (100%), compared to PEP (50%) and CHOW (25%) fed animals. All tissues in the TPN animals contained large quantities of bacteria, while most tissues in the CHOW group were free of bacteria. Bacterial counts in the PEP tissues were intermediate between TPN and CHOW. There were no significant differences between groups for gut weights or mucosal protein content. This study supports a direct relationship between bacterial translocation and mortality in rats following MTX.