On the Pathogenicity of “Pathogenic” Coli Strains

Abstract

In order to elucidate the problems concerning the pathogenicity of “pathogenic” coli, the present work deals with the growth rate of the orally administered organisms, in comparison with that of “non-pathogenic” strains.
1) One of the pathogenic coli strains, O-111: B-4, administered orally to 20 adult volunteers, predominated the intestinal flora in their majority and caused mild diarrheain 10 cases.
2) In adults, “non-pathogenic” strains, when introduced from the outside, were suppressed by pre-existing intestinal flora. In infants, their multiplication was allowed only in a small number of cases, while in newborns their growth and persistence were confirmed invariably.
3) When a Streptomycin resistant coli strain was given orally, together with Streptomycin injection, it replaced pre-existing strains with its active proliferation and persisted in the intestine. The outcome was, however, different, when the pre-existing strains acquired Streptomycin resistance in a short time. They suppressed the exogenic strain, even when the latter belonged to “pathogenic” strains.