The epidemiology of Neisseria gonorrhoeae isolates from Western Australia based on antibiotic resistance and plasmid profiles.

ABSTRACT

Two collections of 90 distinct isolates of Neisseria gonorrhoeae were examined with respect to their plasmid profiles, auxotypes and antibiotic sensitivities to penicillin, erythromycin, streptomycin, spectinomycin, sulphamethoxazole, tetracycline and trimethoprim. The two series, collected from 1976-1981 and from 1985-1986 possessed similar sensitivity patterns except for erythromycin and trimethoprim. The earlier collection of penicillinase producing N. gonorrhoeae (PPNG) was found to be significantly more resistant to both these antibiotics. Within each series the PPNG isolates were more resistant to penicillin and streptomycin than the non-PPNG. All PPNG isolates had the 4.4 X 10(6) dalton penicillinase plasmid and frequently exhibited an auxotype which included a requirement for proline. The frequency of the 24.5 X 10(6) dalton transfer plasmid in the non-PPNG was found to have increased threefold from the early collection to the later one while amongst the PPNG the frequency of the transfer plasmid was seen to decrease. Auxotyping results indicated that the transfer plasmid played a significant role in the spread of the penicillinase plasmid in the early collection. In the later collection a transfer-plasmid-free strain, which required only proline, comprised almost half of the penicillinase producers and this PPNG strain now appears to be adapted to our environment.