Molecular epidemiological investigation of an outbreak of Campylobacter jejuni identifies a dominant clonal line within Scottish serotype HS55 populations

Three molecular typing methods, pulsed-field gel electrophoresis (PFGE), ri botyping, and flagellin (flaA) gene typing, were used to discriminate withi n a group of 28 Campylobacter jejuni, heat-stable serotype 55 (HS55) isolat es derived from cases of campylobacter enteritis occurring throughout Scotl and, including 9 isolates associated with an outbreak. PFGE was found to be most discriminatory, identifying 6 distinct profiles, followed by ribotypi ng (5 profiles), and then flagellin gene typing (4 profiles). The coinciden ce of all three genotypic markers identified a dominant clonal line within the HS55 group, accounting for each of the outbreak strains, and for 9 of t he 19 sporadic strains. A second, closely related, clonal line accounted fo r a further 5 of the sporadic strains, and also included the HS55 reference strain. Identification and monitoring of such clonal lines should facilita te more effective future epidemiological surveillance of C. jejuni.