GENOTYPIC AND PHENOTYPIC IDENTIFICATION OF COLI SURFACE-ANTIGEN 6-POSITIVE ENTEROTOXIGENIC ESCHERICHIA-COLI

A polynucleotide probe comprising the gene encoding a major structural subunit protein of coli surface antigen 6 (CS6) of enterotoxigenic Es cherichia coli (ETEC) was developed. Eighty-nine ETEC isolates were ex amined in parallel with the probe in a colony hybridization assay and in a recently developed polyclonal-antibody-based inhibition enzyme-li nked immunosorbent assay (ELISA). The two assays shelved a high level of concordance in the detection of CS6-positive ETEC (kappa 0.84, P < 0.00001). Thus, 36 of the 89 ETEC isolates were identified as CS6-posi tive by both assays. Six strains that were negative for other coloniza tion factor antigens were positive with the CS6 probe but negative in the ELISA, suggesting lack of surface CS6 expression in these strains. One strain was probe negative but positive in the ELISA, while the re maining 46 strains were negative in both assays. The phenotypic and ge notypic assays will prove useful in vaccine-oriented studies of ETEC d isease.