Trends in gonococcal resistance to antibiotics in Rotterdam, The Netherlands, 1975-86.

The incidence of resistance of Neisseria gonorrhoeae to penicillin and tetracycline was periodically monitored during 1975-86. The incidence of resistance to penicillin (minimum inhibitory concentration (MIC) of more than 1.28 mg/l) of non-PPNG strains remained low (less than 2.5%). The incidence of penicillinase producing N gonorrhoeae (PPNG) strains decreased after a peak of 14% in 1982 to a mean of 8% in more recent years. After a gradual increase, the incidence of tetracycline resistant (MIC of more than 1.28 mg/l) strains has remained stable at around 20% during the past five years. This indicates that a continuing increase in incidence of resistance was not observed in this outpatient clinic.