Twenty-nine strains of penicillinase-producing Neisseria gonorrhoeae (PPNG) and 30 non-penicillinase-producing strains, all isolated in the Gambia, were characterized in terms of their plasmid content, auxotype and protein-I serovar. Sixty-two per cent of the PPNG strains contained the 3·2 MDa penicillinasecoding plasmid, and 38% had the 4·4 MDa plasmid. All the PPNG strains contained the 2·6 MDa cryptic plasmid but lacked the 24·4 MDa conjugative plasmid. In contrast, 46·7% of the non-PPNG strains harboured only the cryptic plasmid while 16·7% contained both the cryptic and conjugative plasmids. Seventeen per cent of the non-PPNG strains contained the conjugative plasmid only and 20% lacked plasmids.
The PPNG and non-PPNG strains also differed in terms of their protein-I serovar. Eighty-six per cent of the PPNG strains belonged to serogroup 1A, whereas the majority (60%) of non-PPNG strains belonged to serogroup IB. There was no significant difference in the auxotypes of the PPNG and non-PPNG strains, with both groups consisting predominantly of prototrophic and prolinerequiring strains, with a minority of strains requiring arginine. When the 59 strains were each characterized in terms of their combined plasmid profile, auxotype and serovar, 39 different combinations were noted, which indicates the heterogeneous nature of the gonococcal population found in the Gambia.