MICROBIAL TRANSLOCATION AND IMPAIRMENT OF MUCOSAL IMMUNITY INDUCED BYAN ELEMENTAL DIET IN RATS IS PREVENTED BY SELECTIVE DECONTAMINATION OF THE DIGESTIVE-TRACT

Objective: To assess the effect of selective decontamination of the di gestive tract (SDD) on intestinal secretory immunoglobulin A (sIgA) co ncentrations in a model of intestinal bacterial overgrowth and bacteri al translocation induced by an elemental diet in rats. Design: Laborat ory study. Setting: University hospital, Germany. Material: 45 specifi c pathogen free female Crl:CDR BR rats. Interventions: For 7 days, 3 g roups of rats were fed orally with standard chow (n = 15), total paren teral nutrition solution (ORAL-TPN, n = 15), or ORAL-TPN plus tobramyc in (20 mg/L) and polymyxin E (25 mg/L) (ORAL-TPN + SDD). Main outcome measures: Bacterial translocation to mesenteric lymph nodes (MLN), num bers of Gram negative enterobacteria and total aerobic bacteria in the caecum, and intestinal concentrations of sIgA. Results: The incidence of bacterial translocation was significantly increased in the group g iven ORAL-TPN (8/15, 53%) compared with the group given chow (1/15, 7% , p < 0.01). Supplementation of ORAL-TPN with SDD reduced translocatio n to 0/15. The ORAL-TPN group had a pronounced overgrowth of aerobic b acteria in the caecum, mainly by Gram negative enterobacteria, which w as prevented by the SDD. The concentrations of intestinal sIgA were si gnificantly reduced in the ORAL-TPN group. SDD resulted in both the so luble and insoluble sIgA fractions in the gut being within the referen ce ranges. Conclusion: SDD prevents Gram negative caecal overgrowth an d translocation to MLN in rodents fed on ORAL-TPN. The significantly r educed mucosal immunity caused by ORAL TPN alone is restored by SDD, a lthough one might have expected a further reduction in sIgA concentrat ions with lower microbial populations than in the ORAL-TPN group. Not only does SDD not seem to affect the mucosa associated immune system a dversely, but also depressed mucosal immunity was restored.