Klebsiella: Taxonomy, nomenclature, and communication

SUMMARY Differences in the delineation of Klebsiella spp. in the United Kingdom from that in the majority of other countries is discussed. An attempt is made to trace and interpret the reasons for these differences and suggestions are made for a rapid resolution of this problem which hazards communication. Cowan (1974), in a brief review of the taxonomy of the genus Klebsiella, recognised seven named species, viz, Klebsiella aerogenes, K. oxytoca, K. edwardsii, K. atlantae, K. pneumoniae (sensu stricto), K. ozaenae, and K. rhinoscleromatis. However, 0rskov (1974), in Bergey's Manual of Determinative Bacteriology (8th edition), described only three species including K. ozaenae, K. rhinoscleromatis, and K. pneumoniae (sensu lato) which embraced those species, K. aerogenes/oxytoca/edwardsii/atlantae, demonstrated by Bascomb et al. (1971) to form a single large cluster of wide spectrum. 0rskov (1974) did not include K. pneumoniae (sensu stricto) which Bascomb et al. (1971) believed on traditional taxonomic grounds could be defined as a separate taxon. At present publications in many United Kingdom medically orientated journals tend to use the binomial K. pneumoniae (sensu stricto) to describe Friedlander's bacillus, and to refer separately to K. aerogenes, K. oxytoca, K. edwardsii, and K. atlantae which fall within the species K. pneumoniae (sensu lato) exclusively referred to in American and many Western European journals. Some British hospital scientists (Barr and Mahood, 1977) accept the close association of several Klebsiella species and refer to K. aerogenes/oxytoca/edwardsii/atlantae as an identi-fiable group which, on the basis of Bascomb's study (Bascomb et al., 1971), would be adequately de-scribed as K. aerogenes. This would result in the definition of two species, K. aerogenes and K. pneumoniae (sensu stricto), in United Kingdom clinical bacteriology literature, in conflict with a single species, K. pneumoniae (sensu lato), in othe