Gonococcal serovar distribution in Stockholm, with special reference to multiple infections and infected partners

Serological classification with co-agglutination, using monoclonal antibody reagents, was used to classify gonococcal strains from 731 consecutive patients seen at the Venereal Outpatients clinic at the Department of Dermatology, Södersjukhuset, Stockholm, up to April 1983. The strains could be divided into two serogroups, WI and WII/III. For the identification of strains belonging to serogroup WI, six Protein IA specific antibody reagents were used, and for strains of serogroup WII/III, seven Protein IB specific antibody reagents. The serogroup WI could be further subdivided into eight different serovariants (serovars), and serogroup WII/III into 30 different serovars. All strains reacted with at least one monoclonal antibody reagent and no strain reacted with both WI and WII/III specific reagents. In both serogroups there was one serovar that was common among women and heterosexual men and another which was more frequent among homosexual men. The 84 contact pairs had strains of corresponding serovar in 95%. Among 258 patients with two or more gonococcal isolates on the same occasion, the isolates from 93% had the corresponding serovar. Repeated gonococcal infections were more frequent among heterosexual men than among women and more frequent among homosexual than among heterosexual men. The serological classification of N. gonorrhoeae is a stable and rapid method and a useful epidemiological tool.