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Penicillinase producing gonococci: a spent force?
Abstract:
Though the incidence of gonorrhoea caused by penicillinase producing Neisseria gonorrhoeae (PPNG) strains at St Mary's Hospital rose rapidly from 1980 to reach 6.2% in 1982, it declined in 1983 (8.6%) and in 1984 (6.5%), a trend that has continued in 1985. The use of penicillinase stable antibiotics or more effective contact tracing are unlikely to be responsible for this recent decline. We have always isolated very few PPNG strains from homosexual men, and the possible effects of the acquired immune deficiency syndrome (AIDS) on sexual behaviour in this group is therefore unlikely to be relevant. We have seen a steady increase in the proportion of PPNG strains carrying the 4.4 megadalton penicillinase plasmid (67% of PPNG strains in 1984). Strains carrying both the 4.4 megadalton plasmid and the 24.5 megadalton conjugal plasmid were very common in 1982, but since then have declined in importance. PPNG strains carrying the 3.2 megadalton plasmid have become less common, and the presence of the 24.5 megadalton plasmid in these strains has not apparently led to their wider dissemination in the community. Whereas the basic pattern of PPNG auxotypes has changed little, since 1982 we have isolated an increasing number of mixed auxotypes with nutritional requirements other than just proline. PPNG strains carrying the 4.4 megadalton plasmid seem to be more resistant to erythromycin, tetracycline, and streptomycin than those carrying the 3.2 megadalton plasmid. Spectinomycin resistance has only occurred in strains carrying the 4.4 megadalton plasmid.
Insights
Penicillinase-producing Neisseria gonorrhoeae (PPNG) incidence declined despite no changes in treatment or contact tracing. The 4.4 megadalton plasmid became more common in PPNG strains, correlating with increased antibiotic resistance.
Area of Science:
- Microbiology
- Infectious Diseases
- Public Health
Background:
- Penicillinase-producing Neisseria gonorrhoeae (PPNG) strains caused a rapid rise in gonorrhoea incidence from 1980 to 1982.
- A subsequent decline in PPNG incidence was observed from 1983 onwards, continuing into 1985.
Purpose of the Study:
- To investigate the reasons behind the declining incidence of PPNG infections.
- To analyze the genetic characteristics and antibiotic resistance patterns of circulating PPNG strains.
Main Methods:
- Surveillance of PPNG incidence and strain characteristics at St Mary's Hospital.
- Plasmid analysis (4.4 and 24.5 megadalton plasmids) and auxotyping of PPNG strains.
- Assessment of antibiotic resistance profiles, including erythromycin, tetracycline, streptomycin, and spectinomycin.
Main Results:
- The decline in PPNG incidence was not attributed to penicillinase-stable antibiotics or improved contact tracing.
- An increasing proportion of PPNG strains carried the 4.4 megadalton penicillinase plasmid, while strains with both 4.4 and 24.5 megadalton plasmids decreased.
- PPNG strains with the 4.4 megadalton plasmid exhibited higher resistance to erythromycin, tetracycline, and streptomycin compared to those with the 3.2 megadalton plasmid. Spectinomycin resistance was exclusively found in strains with the 4.4 megadalton plasmid.
Conclusions:
- The shift in plasmid prevalence, particularly the rise of the 4.4 megadalton plasmid, may be linked to the observed decline in PPNG incidence.
- The increasing prevalence of the 4.4 megadalton plasmid is associated with broader antibiotic resistance, posing a potential future public health challenge.