Neisserial colonisation of the pharynx.

The spectrum of neisserial colonisation of the pharynx was determined from 3557 throat exudates cultured on modified New York City (MNYC) medium. Oxidase positive Gram-negative diplococci (GNDC) were isolated from 1204 (33.8%) of the throat cultures. Neisseria gonorrhoeae, N meningitidis, and N lactamica accounted for 20.3%, 74.2%, and 3.7% of the oxidase positive GNDC respectively. The observed coexistence of gonococci and meningococci in the pharynx (0.39%) was significantly different (p less than 0.001) from the theoretical expected value (1.7%). The prevalence of pharyngeal infection in patients with gonorrhoea was 4.3% for all men, 11% for homosexual men, and 7.9% for women. Despite the risks of disseminated infection and spread to sexual partners, the detection of pharyngeal gonorrhoea is less important than that of endocervical infection in women, urethral infection in heterosexual men, and anorectal infection in homosexual men.