Am. Silva et al., Protective effect of bifidus milk on the experimental infection with Salmonella enteritidis subsp. typhimurium in conventional and gnotobiotic mice, J APPL MICR, 86(2), 1999, pp. 331-336
The ability of Bifidobacterium bifidum from a commercial bifidus milk to an
tagonize Salmonella enteritidis subsp. typhimurium In vivo, and to reduce t
he pathological consequences for the host, was determined using conventiona
l and gnotobiotic mice. Conventional animals received daily, by gavage, 0.1
ml bifidus milk containing about 10(9) cfu B, bifidum and germ-free animal
s received a single 0.1 ml dose. The conventional and gnotobiotic groups we
re challenged orally with 10(2) cfu of the pathogenic bacteria 5 and/or 10
d after the beginning of treatment. Control groups were treated with milk.
Bifidus milk protected both animal models against the challenge with the pa
thogenic bacteria, as demonstrated by survival and histopathological data,
However, to obtain the protective effect in gnotobiotic animals, the treatm
ent had to be initiated 10 d before the challenge. In experimental and cont
rol gnotobiotic mice, Salm. enteritidis subsp. typhimurium became similarly
established at levels ranging from 10(8) to 10(9) viable cells g(-1) of fa
eces and remained at these high levels until the animals died or were sacri
ficed. It was concluded that the protection against Salm, enteritidis subsp
, typhimurium observed in conventional and gnotobiotic mice treated with bi
fidus milk was not due to the reduction of the intestinal populations of th
e pathogenic bacteria.