Variations in the Fermentative Capacity of Neisseriae

Abstract

Apart from the meningococcus and gonococcus, adequate characterization of the aerobic gram-negative diplococci is lacking. The American scheme as described in Bergey's Manual of Determinative Bacteriology (Breed et al?) presents six distinct species, while the British school (Wilson and Miles) favors the establishment of one species, Neisseria pharyngis, which would include all of the saprophytic neisseriae with the possible exception of N. catarrhalis. These divergent interpretations have their origin in numerous publications with conflicting data relative to pigmentation, colonial structure and biochemical activity of gram-negative cocci of the normal nasopharynx. The subject is reviewed by Wilson and Miles. A possible explanation of discrepancies in the biochemical determinations (carbohydrate fermentations) may be found in the manner of performance of such tests and, more specifically, in the nature of the media employed, since individual preference has been exercised in the selection of the basal medium to which carbohydrates were added. It has been found that the nitrogen component of a medium may influence carbohydrate utilization (Orla-Jensen, Sadler, Eagles and Pendray, Katznelson, Burrows and Salmoiraghi). This investigation was undertaken to determine the effect of a variety of basal media on the fermentative ability of 10 cultures of nonpathogenic aerobic neisseriae.