Evaluation of numerical analysis of PFGE-DNA profiles for differentiating Campylobacter fetus subspecies by comparison with phenotypic, PCR and 16S rDNA sequencing methods

Aims: To assess the efficacy of numerical analysis of PFGE-DNA profiles for identification and differentiation of Campylobacter fetus subspecies. Methods and Results: 31 Camp. fetus strains were examined by phenotypic, PC R- and PFGE-based methods, and the 16S rDNA sequences of 18 strains compare d. Numerical analysis of PFGE-DNA profiles divided strains into two cluster s at the 86% similarity level. One cluster contained 19 strains clearly ide ntified as Camp. fetus subsp. venerealis. The other cluster comprised 12 st rains, of which 10 were unambiguously identified as Camp. fetus subsp. fetu s. The remaining two strains were identified as Camp. fetus subsp. venereal is by either phenotypic or PCR methods, but not both. At higher similarity levels, clusters containing isolates from each of two countries were identi fied, suggesting that certain clones predominate in certain geographical re gions. Conclusions: Numerical analysis of PFGE-DNA profiles is an effective method for differentiating Camp. fetus subspecies. Significance and Impact of the Study: Critical comparison of PFGE, PCR, 16S rDNA sequencing and phenotypic methods for differentiation of Camp. fetus subspecies was attained. Novel phenotypic markers for distinguishing subspe cies were identified. Evidence for dominant clones of each subspecies in ce rtain countries was provided.