Characterization of atypical aerobic gram-negative cocci isolated from humans.

Six atypical aerobic gram-negative cocci, isolated from humans, were classified taxonomically by genetic relatedness (DNA base pairs and DNA homology), fatty acid content, pigment absorption profile, and other physiological and biochemical characteristics. One strain (M448), which produced acid only from glucose, was identified as Neisseria meningitidis; one strain (CH), which produced acid from glucose, maltose, and sucrose, was identified as N. gonorrhoea; Branhamella catarrhalis was confirmed in a case of acute meningitis; N. canis was identified in a cat bite wound; and representative isolates of a proposed new pigmented species were found to have genetic affinities with N. meningitidis and N. perflava.