Interlaboratory comparative study of the numerical analysis of one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoretic protein patterns of Campylobacter strains.

Twenty-nine bacterial strains of the genus Campylobacter were examined independently at two collaborating institutes, the National Collection of Type Cultures, London and the Laboratorium voor Microbiologie, Rijksuniversiteit Gent. The one-dimensional polyacrylamide gel electrophoretic protein patterns of the strains were analysed using computerised numerical methods which employed a correlation coefficient and a clustering algorithm. The electrophoretic methods used at the two institutes included both major differences such as gel composition and running conditions and minor differences in buffer composition. Although the algorithm on which similarity and clustering were computed were the same, the detailed treatment of scan patterns differed. The resulting protein patterns in the gels differed markedly in appearance but after numerical analysis the two systems were equally effective in their ability to speciate the strains. There were, however, differences in the relationships between the species defined at the two institutes and these were at least partly due to the different background subtraction methods employed. In conclusion, the portability and reproducibility of the two systems for identification was demonstrated but for definitive classification further standardization may be required.