Neisseria lactamica is a gram-negative diplococcus bacterium.

Uniquely among the Neisseria they are able to produce β-D-galactosidase and ferment lactose.

[1] This species is most commonly carried by young children.

There is an inverse relationship between colonisation by N. lactamica and Neisseria meningitidis.

[2] Carriage of N. lactamica has been associated with decreased incidence of invasive meningococcal disease.