[Pathogenicity of E. coli: biological aspects and problems related to laboratory diagnosis (author's transl)]

The biological properties which may contribute to the pathogenicity of E. coli are reviewed in this article. Specifically the following topics are discussed in detail: 1) adhesion to the intestinal epithelial cells, 2) production of enterotoxins, 3) invasiveness of and ability to multiply within the epithelial cells, 4) insensitivity to complement lysis or inability to activate the alternative pathway of complement, 5) resistance to phagocytic killing. The various techniques which might be of potential usefulness in the clinical laboratory to test the parameters of the pathogenicity of E. coli are briefly outlined. The dissociation between the definition of pathogenicity, as established on the basis of the results of E. coli serotyping, and the criteria of pathogenicity listed above is brought to the attention of the reader. As specificity regards the toxinogenicity, what emerged from a survey of the literature, was that only one of the so called "enteropathogenic" strains of E. coli, according to the serotype classification, was found to produce an enterotoxin.