Epidemiology of penicillinase-producing Neisseria gonorrhoeae in Liverpool from 1977 to 1982.
After the 1976 outbreak of penicillinase-producing Neisseria gonorrhoeae (PPNG) infections had been controlled, less than 1 per cent of cases of gonorrhoea in Liverpool in 1977 and 1978 were caused by PPNG. Thereafter the steady increase in PPNG infections to 5.6 per cent of all cases in 1982 was associated with marked changes in epidemiological pattern, plasmids and auxotypes. In 1976 nearly all PPNG infections were acquired by young black males living in the inner city from women frequenting clubs; the PPNG were all of the African 3.2 megadalton (MD) plasmid type and of arginine-requiring auxotype. Between 1977 and 1982 female patients were increasingly ship girl prostitutes associating with seamen who constituted more than 50 per cent of the male patients. These men and other travellers introduced PPNG into Liverpool from the Far East and West Africa. In 1978 PPNG of the Asian type with 4.4 MD plasmid with or without 24.5 MD transfer plasmids were isolated in Liverpool where in 1979 all PPNG carried 4.4 MD and 24.5 MD plasmids. In 1982 strains of the 'new' African type with 3.2 and 24.5 MD plasmids were isolated as were PPNG of the Asian type that had been acquired in West Africa. Auxotyping of the 1982 isolates showed that none were arginine-requiring but three other types were identified: proline-requiring: proline-arginine-requiring; non-requiring. For the control of PPNG, a strategy based on constant vigilance, appropriate diagnostic procedures, rapidly effective treatment and determined contact tracing is needed.