Studies on the adhesive factors of pathogenic strains of escherichia coli isolated from man

The present study was designed to answer a number of questions related to the presence and function of known or suspected adhesive factors in strains of E.coli. A total of 808 E.coli strains isolated from intestinal and extraintestinal sources in man were tested for the ability to agglutinate human, calf and guinea-pig RBC in the presence and absence of D-mannose, and for the presence of CFA/I and CFA/II by slide agglutination and immunodiffusion techniques using specific antisera. The biochemical and serological characteristics of CFA/I and CFA/II positive strains were examined, and related to the genetic control of these adhesive factors. The morphological characteristics of these fimbriate antigens was investigated by electron microscopy studies. Strains that did not possess CFA/I or CFA/II, but were able to cause MRHA of human and/or calf RBC, were further examined by serological methods for the presence of other adhesive factors. An in vitro assay using HEp-2 tissue culture cells was developed to test the adhesive ability of strains of E.coli able and unable to cause MPJLA or MSHA. The relationship between the biochemical and genetic characteristics of the E.coli strains and their ability to adhere to HEp-2 cells was also investigated.