A simple view of nocardial taxonomy

Abstract

Nocardial taxonomy, like that of other actinomyeete genera, has undergone all the viscissitudes of doubt associated with years of inadequate and sometimes inappropriate methodology. This is reflected by the great expansion of species names allocated to the genus over the first two thirds of this century (Buchanan, Holt & Lessel, 1966), followed by the contraction achieved in the list of approved bacterial names in 1980 (Skerman, McGowan & Sneath, 1980). Created by Trevisan in 1889 for five species, modern taxonomists would now allocate some 20 species to the genus, including only one of Trevisan's original five species (Table 1). As an actinomycetc genusNocardiahas suffered from two particular disadvantages. First in having an apparently distinctive nocardioform morphology on the basis of which organisms were referred to this genus long after crude morphology lost its importance in many other genera. Second in having an unfortunate type species,Nocardia farcinica, with no really well accredited type strain.