Discrimination of Campylobacter jejuni isolates by fla gene sequencing

Comparison of the entire coding sequence of flaA (1,764 nucleotides) from 15 isolates of Campylobacter jejuni showed two regions of high variability, one region approximately from base positions 700 to 1,450 and a short variable region (SVR) from base positions 450 to 600. Parsimony analysis of the SVR sequences yielded a dendrogram similar to that which was derived by analysis of the entire gene. PCR was used to generate templates, and the SVR was sequenced with primers constructed to hybridize to conserved flanking sequences. The SVRs of 22 isolates of C. jejuni from four outbreaks that have been well characterized and a larger panel of isolates from three additional outbreaks were sequenced. Analysis of the nucleotide sequences produced results that grouped the isolates very similarly to other subtyping techniques. Sequence data were also generated for isolates from three additional outbreaks. Categorizing the isolates by fla SVR DNA sequence placed them in epidemiologically relevant groups. Sequence analysis of the C. jejuni flaA SVR may be a useful tool for epidemiologic investigations and could complement or replace serotyping and other subtyping methods.