Anogenital non-gonococcal neisseriae: prevalence and clinical significance

Over a 13-year period non-gonococcal neisseriae (NGN) were isolated from 114 of 88,670 patients (0.13%) screened for anogenital gonorrhoea at a Genitourinary Medicine Unit. During the same period there were approximately 9000 anogenital gonococcal infections (10%). The prevalence of NGN was 0.09% (27/31,500) in women, 0.04% (20/52,800) in heterosexual men and 1.5% (67/4370) in homosexual men: the differences in prevalence between women and heterosexual men (P < 0.01) and between heterosexual patients and homosexual men (P < 0.001) are highly significant. Neisseria meningitidis was isolated most frequently and accounted for 85% (99/114) of the NGN. Whenever possible, N. meningitidis was serogrouped and its occurrence correlated with patient symptoms. Eleven of 18 heterosexual men who had meningococci isolated from their urethras had urethritis but co-existing chlamydial infection was excluded in only 5. None of 9 women with cervical colonization had clinical evidence of pelvic inflammation. Only one of 49 men with rectal colonization had proctitis. The management of anogenital NGN infection is discussed in relation to our findings and those of previously published studies. Within each patient group the prevalence and incidence of anogenital NGN were similar at the beginning and end of the study period indicating that levels have not been influenced by the advent of AIDS.