Typing of Neisseria gonorrhoeae by auxotype, serovar and lectin agglutination

A total of 267 strains of Neisseria gonorrhoeae, comprising 129 serogroup IA and 138 serogroup IB, isolated in Edinburgh over a two-year period were analysed to assess the discrimination given by three typing methods: auxotyping; serotyping using the Genetic Systems (GS) and Pharmacia (PH) monoclonal antibody panels; and lectin agglutination. Each typing system was assessed individually and in combination. Serotyping subdivided the strains into 14 GS and 18PH serovars. Auxotyping (Aux) yielded 11 separate auxotypes while lectin agglutination yielded 22 different reaction patterns (LP). The standard auxotype/GS serovar (A/S) classification system yielded 37 classes. Lectin agglutination allowed further subdivision of the main A/S classes. AHU/IA-2 strains,which accounted for 70% of IA strains, yielded nine different lectin patterns (A/S/LP classes). Likewise, lectin agglutination allowed subdivision of the main IB A/S classes. NR/IB-1, NR/IB-2 and NR/IB-3, which accounted for 28%, 38% and 20% respectively of the IB strains, yielded 7, 7 and 6 A/S/LP classes respectively. It was concluded that lectin agglutination is a useful adjunct to the standard A/S classification system for studying the micro-epidemiology of gonococcal infection.