Identification of Escherichia coli flagellar types by restriction of the amplified fliC gene.

A total of 182 strains of Escherichia coli (133 reference strains, 22 clinical strains, nine nonmotile strains and 18 strains derived from K-12) were characterized by HhaI restriction of the amplified flagellin gene (fliC). The amplified fliC product was a single band between 0.9 and 2.6 kbp. With the collection of reference strains which represented 48 flagellar types (H-types), a total of 62 patterns (F-types) were observed after HhaI restriction. A single F-type was associated with each of 39 H-types and more than one F-type was associated with the other nine H-types. Antigenically related H-types 12 and 45 gave a single F-type. The determination of HhaI-fliC F-types could allow deduction of all H-types and subdivision of some of these. Application of this identification system to 22 E. coli clinical isolates yielded nine F-patterns and the deduced H-types were confirmed by serotyping in all cases. Nine nonmotile strains were studied and their F-types were also identified. The proposed determination of fliC restriction patterns should be helpful for epidemiological studies.