Ribosomal Ribonucleic Acid Cistron Similarities and Deoxyribonucleic Acid Homologies of Neisseria , Kingella , Eikenella, Simonsiella, Alysiella, and Centers for Disease Control Groups EF-4 and M-5 in the Emended Family Neisseriaceae

We detected distinct taxonomic relationships among the true Neisseria species, Kingella kingae, Kingella denitrificans, Eikenella corrodens, all Simonsiella species, the type strain of Alysiella filiformis, and members of Centers for Disease Control groups EF-4 and M-5. All these taxa constitute one large separate cluster having high levels of ribosomal ribonucleic acid cistron similarity (thermal denaturation temperature range, 74 to 81°C) in ribosomal ribonucleic acid superfamily III. There are at least four subbranches. We found high deoxyribonucleic acid (DNA)-DNA homology values between Neisseria gonorrhoeae and some other true Neisseria species and within the following species: Simonsiella muelleri, Simonsiella crassa, Simonsiella steedae, Kingella denitrificans, and Eikenella corrodens. All of the members of this large cluster have genome base compositions in the range from 42.8 to 57.7 mol% guanine plus cytosine. The molecular complexities of the genomic DNAs are 2.2 x 109 to 2.7 x 109 for Simonsiella and Alysiella species and 1.4 x 109 to 1.8 x 109 for the other members of this large cluster. We formally propose that this large cluster represents the emended family Neisseriaceae containing the following genera and groups: Neisseria, Kingella (not the generically misnamed Kingella indologenes), Eikenella, Simonsiella, Alysiella (not some misnamed strains), and Centers for Disease Control groups EF-4 and M-5. The genera and subgenera Acinetobacter, Moraxella, Branhamella, Psychrobacter, the false neisseriae, and Kingella indologenes should be removed from the Neisseriaceae, as they belong to superfamilies I and II.