Neisseria lactamica

Neisseria lactamica is a gram-negative diplococcus bacterium. It is strictly a commensal species of the nasopharynx. 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.[3] However, resistance to penicillin and other beta-lactams may be transmitted from commensal neisseriae such as Neisseria lactamica to disease-causing Neisseria meningitidis by the process of genetic transformation.[4]