COLONIZATION OF STREPTOMYCIN-TREATED MICE BY AEROMONAS SPECIES

Streptomycin-treated adult mice were investigated as a possible model for studying the enteropathogenicity of Aeromonas species. C57BL mice pre-treated with streptomycin (5.0 g/L drinking water, 48 hours) recei ved a single intragastric dose (10(10) bacteria/10.5 mL) of one of six well-characterized, toxin-producing, human diarrhoeal isolates of A, veronii biovar sobria (n=3) or A. hydrophila (n=3). Their faeces were examined for Aeromonas for 10 days postchallenge, All strains colonize d the antibiotic-treated mice. Colonization did not occur in mice whic h did not receive streptomycin. Strains of A, hydrophila were recovere d in greater numbers than strains of A. veronii biovar sobria, and col onized (greater than or equal to 10(3) cfu/g of faeces) a greater prop ortion of mice at day 10. Strains of the latter species, however, were more adherent in cell line assays used as models of intestinal adhesi on, A. hydrophila strains localized in the large intestine and appeare d not to be cell associated, This study, therefore, points to species- related differences in intestinal colonization mechanisms, The strepto mycin-treated adult mouse model may prove useful for further investiga tion of some of these mechanisms, Diarrhoeal symptoms were, however, n ot produced in this model.