Taxonomy of anaerobes: present state of the art.

Results of nucleic acid studies, which indicate relationships among strains and species more clearly than do usual phenotypic tests, have led to new bacteriologic nomenclature. Some major changes in Bacteroides include the recognition of three species (Bacteroides melaninogenicus, Bacteroides denticola, and Bacteroides loescheii) formerly grouped in B. melaninogenicus subspecies melaninogenicus; two species (Bacteroides intermedius with two closely related homology groups and Bacteroides corporis) formerly grouped together as B. melaninogenicus subspecies intermedius; and two species (Bacteroides buccae and Bacteroides oris) formerly thought to be human isolates of Bacteroides ruminicola subspecies brevis. Former subspecies of Bacteroides fragilis have been elevated to species rank; and Bacteroides uniformis and an unnamed group ("3452A"), recognized. A new genus, Capnocytophaga, with three species, is composed of strains formerly classified as Bacteroides ochraceus or Centers for Disease Control (CDC) group DF-1. Strains previously thought to be human isolates of "Vibrio succinogenes" and related organisms that derive energy by reduction of fumarate or nitrate with formate or hydrogen have been reclassified in Bacteroides (Bacteroides gracilis), Campylobacter (Campylobacter concisus), or in a new genus, Wolinella.