Probiotic supplementation reduces the risk of bacterial translocation in experimental short bowel syndrome

BACKGROUND/PURPOSE

Probiotics are live organisms that survive passage through the gastrointestinal tract and have beneficial effects on the host. Lactobacillus and Bifidobacterium have been recommended for cholesterol lowering, acute diarrhea, prevention of cancer, or inflammatory bowel disease. On the other hand, after massive bowel resection, bacterial overgrowth is frequent and favors bacterial translocation (BT). The possible beneficial effects of Bifidobacterium lactis (BL) administration on BT in experimental short bowel syndrome (SBS), have not been investigated. The aim of this study was to test the hypothesis that BL administration decreases BT in SBS in animals fed orally.

METHODS

One hundred twenty-eight adult Wistar rats fed orally with standard rat chow and tap water "ad libitum" were maintained in individual metabolic cages for 10 days and divided into 3 groups: control group (n = 71): nonmanipulated animals; RES group (n = 39): 80% gut resection from 10 cm beyond the angle of Treitz to 10 cm above the cecum; RES-PRO group (n = 18): same resection and daily 7.8 x 10(8) CFU B Lactis administration, after orogastric intubation. At the end of the experiment they were killed, and mesenteric lymph nodes (MLN) and peripheral and portal blood specimens were recovered and cultured. Bacterial identification in blood was made by conventional methods, and MLN culture was considered positive with a growth over 100 CFU/g.

RESULTS

Bacterial translocation was detected in 6% of control group rats. The incidence of BT in the RES group was 87% (34 of 39), whereas only 50% (9 of 18) of RES-PRO animals had BT (P <.05). The relative risk reduction (RRR) was 0.43 (95% Cl 0.14 to 0.72), and the number needed to treat (NNT) was 3 (95% Cl 2 to 8). In other words, animals that received BL had the risk of BT reduced by 43% (RRR of 0.43), and of every 3 animals treated, 1 is expected to be free of BT (NNT of 3).

CONCLUSION

Administration of B Lactis reduces the incidence of BT in adult Wistar rats after 80% gut resection.

Effect of growth hormone, epidermal growth factor, and insulin on bacterial translocation in experimental short bowel syndrome

BACKGROUND/PURPOSE

An adaptive process starts in the remaining intestine after massive resection, and several trophic factors including growth hormone (GH), epidermal growth factor (EGF), and insulin (INS) have been shown to have a positive effect on it. Bacterial translocation (BT) is frequent after extensive small bowel resection, but the effects of GH, EGF, or INS have not been investigated in experimental short bowel syndrome (SBS). This study tests the hypothesis that GH, EGF, or INS decrease BT in SBS in rats with parenteral nutrition (PN).

METHODS

Thirty-eight adult Wistar rats underwent central venous cannulation and were assigned randomly to 1 of 4 groups receiving for 10 days 4 treatment regimes: (1) PN group (n = 10): fasting, all-in-one PN solution (300 mL/kg/24 h, 280 kcal/kg/24 h), 80% gut resection including ileo-cecal valve; (2) GH group (n = 9): fasting, same PN regime and resection, GH (1 mg/kg/d, subcutaneously); (3) EGF group (n = 9): fasting, PN, resection, EGF (150 microg/24 h intravenously); (4) INS group (n = 9): fasting, PN, resection, INS (1 UI/100 g/24 h subcutaneously). At the end of the experiment they were killed, and mesenteric lymph nodes (MLN) and peripheral and portal blood samples were recovered and cultured. Several fragments of intestine were taken to determine cell proliferation (PCNA index) and morphometric parameters (villous height, crypt depth).

RESULTS

GH, EGF, and INS groups showed a 28%, 29%, and 30% increase in gut mucosal thickness, and PCNA index rose 21%, 20%, and 25%, respectively in comparison with PN controls. Bacterial translocation to peripheral blood was detected in 0% of PN animals and in 44%, 40%, and 28% of GH, EGF, or INS rats, respectively (P < .05). No differences were found in BT in MLN or portal blood among groups.

CONCLUSION

Administration of GH, EGF, or INS improves gut mucosal structure in rats with SBS under PN, but, surprisingly, the incidence of BT detected in peripheral blood was increased rather than decreased in animals receiving these treatments.

Bacterial translocation is favored by the preservation of the ileocecal valve in experimental short bowel with total parenteral nutrition

Sepsis in short-bowel syndrome (SBS) is in part due to bacterial translocation (BT). Parenteral nutrition (PN) is often necessary in SBS and promotes BT. The aim of this study was to asses the effect of the presence or absence of ileocecal valve (ICV) on BT in parenterally-fed rats with massive intestinal resection. Sixty-five adult Wistar rats underwent central venous cannulations and were randomly assigned to one of five groups receiving for ten days five treatment regimes: Sham (n = 17) standard rat chow + i.v. saline. PN (n = 17) fasting + PN. Res-Sham (n = 10) standard rat chow + i.v. saline + 80% gut resection. Res-PN (n = 11) fasting, PN + 80% gut resection. Res-ICV-PN (n = 10) fasting, PN + 80% gut resection including ICV. At the end of the experiment they were euthanized and mesenteric lymph nodes (MLN), spleen and peripheral and portal blood specimens were recovered and cultured. BT was found in 47% of PN animals, 91% of Res-PN rats, 100% of Res-Sham group and 60% of Res-ICV-PN animals, but not in Sham ones. 97% of BT+ animals had positive cultures in MLN and/or portal blood, whereas germs beyond liver were detected in 30% of Res-Sham, 37% of PN, 50% of Res-PN and 0% of Res-ICV-PN rats. The present study confirms that both massive intestinal resection and PN promote BT. In addition, it shows that animals deprived of ICV have lower incidence of BT in this setting than those with it and that the germs do not reach in them peripheral blood in the same proportions as in ICV-intact animals. These results suggest that the presence of an intact ICV favor BT in parenterally-fed rats with massive intestinal resection.

Effect of growth hormone on bacterial translocation in experimental short-bowel syndrome

Despite the adaptive process triggered in the remaining intestine by massive bowel resection, bacterial translocation (BT) is frequent under these conditions. Several trophic factors, including growth hormone (GH), are involved in the process of adaptation in short-bowel syndrome (SBS). However, the effect of GH on BT has not been investigated experimentally. The aim of this study was to test the hypothesis that GH administration prevents BT in rats with SBS receiving only parental nutrition (PN). Nineteen adult Wistar rats underwent central venous cannulation and were randomly assigned to one of two groups receiving for 10 days two treatment regimes: PN group (n = 10): fasting, all-in-one PN solution (300 ml. kg. 24 h, 280 kcal/kg. 24 h), 80% gut section including ileocecal valve; GH group (n = 9): fasting, same PN regime and resection plus GH 1 mg/kg s.c). At the end of the experiment, the rats were killed and mesenteric lymph nodes (MLN) and samples of systemic and portal blood were obtained and cultured. Several samples of full-thickness jejunal wall were taken for determining cell proliferation index (PCNA) and mucosal thickness. Jejunal mucosal thickness increased by 30% and PCNA index by 35% in GH-treated rats in comparison with those treated with PN alone. However, contrary to our expectations, BT expressed by positive culture of intestinal flora in portal blood, MLN, or systemic blood was found in 60% of PN and 87% of GH animals (P = 0.1). Translocation to the general circulation expressed by the presence of organisms in systemic blood was detected in 0% of PN and 44% of GH rats (P < 0.05). Although exogenous GH improves gut mucosal structure in rats with SBS treated with PN, it seems to increase rather than decrease mucosal permeability to intestinal bacteria.

Bacterial translocation and T-lymphocyte populations in experimental short-bowel syndrome

Bacterial translocation (BT) accounts in part for sepsis in short-bowel syndrome in which total parenteral nutrition (TPN) is routinely necessary. TPN "per se" facilitates BT and it has been suggested that decreased T-lymphocyte populations (TLP) in newborn rabbits and nude mice promote BT as well. We have tested the hypothesis that BT and modifications in TLP are to be expected in rats subjected to TPN and gut resection. Forty-five adult Wistar rats underwent central venous cannulations and were randomly assigned to one of three groups receiving for ten days three treatment regimes: - Group Sham (n = 17) oral intake of rat chow + saline (300 ml/kg/24 h) through a jugular vein catheter. - Group TPN (n = 17) fasting + infusion of all-in-one TPN solution (300 ml/kg/24 h). - Group RES (n = 11) fasting, same TPN regime + 80% gut resection. At the end of the experiment they were sacrified and specimens (peripheral and portal blood, spleen and mesenteric lymph nodes) were recovered, cultured and/or assessed for CD4+ and CD8+. Bacterial translocation was found in 47% of TPN animals, 92% of RES rats, but not in SHAM ones. Lymphocyte populations were not different in BT+ (n = 8) or BT- (n = 9) rats in the TPN group. TPN and resected animals showed a rise in CD4+ and a drop in CD8+ (then a better CD4+/CD8 ratio) when comparing with SHAM group rats. From this data we may conclude that: 1) BT is frequent if TPN is administered, and constant in resected animals. 2) No apparent relationship between the proportions of CD4+ and CD8+ lymphocytes and BT could be shown in TPN group. 3) High CD4+/CD8+ ratio in TPN and RES groups demonstrate that BT is possible even having good TLP.