Background: The enteric bacterial flora has been implicated in the pathogen
esis of enterocolitis and colon cancer in C57BL/6 IL-10 knockout mice. Prob
iotic Lactobacilli modify the enteric flora and are thought to have a benef
icial effect on enterocolitis. We conducted a controlled feeding trial in I
L-10 knockout mice using the probiotic Lactobacillus salivarius ssp. saliva
Aim: To determine the effect of probiotic consumption on the gastrointestin
al microflora, tumour development and colitis in IL-10 knockout mice.
Methods: Twenty IL-10 knockout mice were studied (10 consumed probiotic org
anisms in milk and 10 consumed unmodified milk) for 16 weeks. Faecal microb
ial analysis was performed weekly to enumerate excretion of the probiotic U
CC118, total lactobacilli, Clostridium perfringens, bacteroides, coliforms,
bifidobacteria and enterococci. At sacrifice, the small and large bowel we
re microbiologically and histologically assessed.
Results: L. salivarius UCC118 was detected in faeces from all mice in the p
robiotic fed group, but not the control group. Faecal coliform and enteroco
cci levels were significantly reduced in probiotic fed animals compared to
the controls (P < 0.05). At sacrifice, a significant reduction in C. perfri
ngens numbers was observed in the test mice (P < 0.05). There were no fatal
ities in the test group compared to two deaths from fulminant colitis in th
e control group. Only one test mouse developed colonic adenocarcinoma compa
red to five in the control group. Test animal mucosal inflammation consiste
ntly scored lower than that of the control mice.
Conclusion: In this placebo controlled trial, modification of enteric flora
in IL-10 knockout mice by probiotic lactobacilli was associated with reduc
ed prevalence of colon cancer and mucosal inflammatory activity.