Abstract
In January 1981 the incidence of penicillinase producing Neisseria gonorrhoeae (PPNG) strains in Amsterdam had increased to 18% of all new cases of gonorrhoea. Auxanographic typing in combination with plasmid determination of 729 PPNG strains showed that in 1981 the predominant and endemic types were those with the Africa plasmid and transfer factor which were non-requiring and inhibited by phenylalanine. In 1982 proline requiring strains with the Asia plasmid and transfer factor increased after being imported and spread by prostitution. Four different plasmid patterns and 12 auxotypes were distinguishable. Unusual auxotypes of both African and Asian plasmid types are frequently imported, some disappearing soon after their introduction into Holland but others providing an opportunity to trace sources and contacts. Prostitution and the biological properties of PPNG strains seem to play an important role in their spread. Only 2.6% of them were isolated from homosexual men. In areas where PPNG strains are prevalent, auxotyping is an important tool in their surveillance.