Taxonomy of Campylobacter, Arcobacter, Helicobacter and related bacteria: current status, future prospects and immediate concerns.

Abstract

The taxonomy of the genus Campylobacter has changed dramatically since its inception in 1963. At that time the genus comprised just two species. At present, taxa that were once assigned to Campylobacter may belong to one of over 50 species distributed among six genera. Most of these taxa belong to a phylogenetically distinct group referred to as either ribosomal RNA (rRNA) superfamily VI or the epsilon division of the class Proteobacteria. The taxonomic diversity of the group is matched by the diverse habitats in which they may be found, and by the wide range of diseases that they are associated with. Recognition of their clinical and economic importance has resulted in intense interest in the group, and the application of increasingly sophisticated isolation, detection and chemotaxonomic methods continues to elucidate new aspects of their biodiversity. However, despite the advances in new bacterial systematics, there remain a number of important issues concerning the classification of various campylobacterial taxa that require careful consideration. Ultimately, these issues are relevant to many working in the field of applied microbiology, including clinicians, veterinarians, epidemiologists and taxonomists. The purpose of this article is briefly to review the major developments in the taxonomy of Campylobacter from its inception to the present day; summarize the most recent changes in the field; analyse current topical issues of special relevance to applied microbiologists, including identification of the bacteria; and speculate on future prospects for campylobacterial taxonomy.