Safety assessment of potential probiotic lactic acid bacterial strains Lactobacillus rhamnosus HN001, Lb. acidophilus HN017, and Bifidobacterium lactis HN019 in BALB/c mice

The general safety of immune-enhancing lactic acid bacteria (LAB) strains L actobacillus rhamnosus HN001 (DR20(TM)), Lb. acidophilus HN017, and Bifidob acterium lactis HN019 (DR10(TM)) was investigated in a feeding trial. Group s of BALB/c mice were orally administered test LAB strains or the commercia l reference strain Lb. acidophilus LA-I at 2.5 X 10(9), 5 X 10(10) or 2.5 X 10(12) colony forming units (CFU)/kg body weight/day for 4 weeks. Througho ut this time, their feed intake, water intake, and live body weight were mo nitored. At the end of the 4 week observation period, samples of blood, liv er, spleen, kidney, mesenteric lymph nodes, and gut tissues (ileum, caecum, and colon) were collected to determine: haematological parameters (red blo od cell and platelet counts, haemoglobin concentration, mean corpuscular vo lume, mean corpuscular haemoglobin, and mean corpuscular haemoglobin concen tration); differential leukocyte counts; blood biochemistry (plasma total p rotein, albumin, cholesterol, and glucose); mucosal histology (epithelial c ell height, mucosal thickness, and villus height); and bacterial translocat ion to extra-gut tissues (blood, liver, spleen, kidney and mesenteric lymph nodes). DNA finger printing techniques were used to identify any viable ba cterial strains recovered from these tissues. The results demonstrated that 4 weeks consumption of these LAB strains had no adverse effects on animals ' general health status, haematology, blood biochemistry, gut mucosal histo logy parameters, or the incidence of bacterial translocation. A few viable LAB cells were recovered from the tissues of animals in both control and te st groups, but DNA fingerprinting did not identify any of these as the inoc ulated strains. The results obtained in this study suggest that the potenti ally probiotic LAB strains HN001, HN017, and HN019 are non-toxic for mice a nd are therefore likely to be safe fur human use. (C) 2000 Elsevier Science B.V. All rights reserved.