Feeding by mucin and intestinal growth of some enteric bacterial pathogens.

Enteroinvasive Escherichia coli, Salmonella typhi-murium, Shigella sonnei, Shigella flexneri, as well as E. coli K-12 show dose dependent growth in minimal medium completed with purified hog gastric "Granular Mucin". This ability is based on alpha-galactosidase production: defective, melibiose (and galactose) non-fermenting K-12 mutant were unable to utilize mucin. The viability of the parent K-12 strain in the cecal content of mice is significantly higher than that of its Mel- mutant phenotype. In mixed infections of mice the parent strain was the only one to be able to establish a monoflora against its Mel- or Gal- mutants. Among other mechanisms, the growing ability in the intestinal mucous layer may be an additional virulence factor when the enteric pathogens are exposed to a competitive antagonism of the normal flora.