Deoxyribonucleic acid relatedness among Neisseria gonorrhoeae, N. meningitidis, N. lactamica, N. cinerea and "Neisseria polysaccharea".

Deoxyribonucleic acid relatedness studies (S1 nuclease method with DE-81 filters method) indicated that Neisseria gonorrhoeae, N. meningitidis, N. lactamica and "N. polysaccharea" form a single genospecies, in which four subspecies can be delineated. However, from a clinical and practical viewpoint, it seems desirable to maintain N. gonorrhoeae, N. meningitidis, N. lactamica and "N. polysaccharea" as separate species. N. cinerea is a valid species, closely related to N. gonorrhoeae, N. meningitidis, N. lactamica and "N. polysaccharea". These five species were O to 46% related to the other known species of the genus Neisseria.