Serology of Neisseria gonorrhoeae. Demonstration of strain-specific antigens by immunoelectrophoresis, immunofluorescence and co-agglutination techniques

Gonorrhoea in men with homosexual contacts. Serogroups of isolated gonococcal strains related to antibiotic susceptibility, site of infection, and symptoms

In 37 homosexual men the incidences of urethral, rectal, and pharyngeal gonorrhoea were 45.9%, 56.8%, and 27% respectively. Local symptoms were present in all men with urethral gonorrhoea but in only 25% of those with pharyngeal or rectal gonorrhoea or both. Infection at two sites was found in 29.7% of the patients. Forty-nine gonococcal isolates from the 37 patients were serogrouped by coagglutination into one of the serogroups WI, WII, and WIII, and their susceptibility to benzylpenicillin, ampicillin, cefuroxime, doxycycline, and spectinomycin tested. Only one gonococcal isolate from each patient was counted when two isolates belonged to the same serogroup and had the same antibiotic susceptibility. Thus, 15.4%, 76.9%, and 7.7% of the gonococcal strains belonged to serogroups WI, WII, and WIII respectively. There was a significantly lower incidence of WI strains and a significantly higher incidence of WII strains among men with homosexual contacts than among other patients with gonorrhoea from the same geographical region. Gonococcal strains of serogroup WI were significantly more resistant to all antibiotics tested, except to spectinomycin, than randomly chosen WI strains. Among WII and WIII strains the incidence of diminished susceptibility to all antibiotics tested was about the same.

Evaluation of the coagglutination test for the identification of Neisseria gonorrhoeae in primary cultures

The coagglutination (COA) test for the identification of Neisseria gonorrhoeae was compared with immunofluorescence and sugar degradation tests on 1710 gonococcal isolates, 72 of which produce beta-lactamase. The COA test gave a positive result for 98.6% of the strains. Treatment of suspensions with Streptomyces enzyme reduced the incidence of inconclusive results due to autoagglutination to 1.2%. Cross-reactivity of the gonococcal antiserum was minimised by absorption with meningococci and Moraxella species. The COA provide a simple, quick, and reliable method for identifying N gonorrhoeae in culture.