Contributor: Gordon K. Klintworth
Infections due to Neisseria can result from several species. The most important are Neisseria gonorrhoeae and Neisseria meningitidis, which cause gonorrhea and meningococcal meningitis  [meningitis - meningococcal]. Other species of Neisseria (Neisseria flavescens)  have been found in association with meningitis (Neisseria flavescens, Neisseria lactamica, Neisseria subflava), endocarditis (Neisseria lactamica), pneumonia (Neisseria mucosa) and septicemia (Neisseria flavescens).  Neisseria infections provoke predominantly a polymorphonuclear cytologic response. It may cause a purulent conjunctivitis and has all of the following characteristics. Extremely susceptible to thermal changes. The organism is no longer sensitive to penicillin. Silver nitrate prophylaxis against ophthalmia neonatorum due to Neisseria gonorrhoeae was introduced by Crede in 1884, when he instilled a drop of 2% silver nitrate into the cul-de-sac of a newborn. Neisseria once a common cause of ophthalmia neonatorum, is no longer common in many countries because of adequate prophylaxis protocols.