PPNG strains

Objective-To analyse temporal changes in gonococcal serovar patterns in Stockholm during a two year study period (1987-1989) to elucidate the dynamics ofgonorrhoea epidemiology. Design-The study population comprised 857 patients with culture proven gonorrhoea and with serotyped gonococcal isolates. The probable geographical origin of the infection was determined in 690 ofthe patients. Results-A total of 108 PhIGS-serovars were identified. Most (73%) of the serovars were recognised only during one or two quarters of the study period and comprised 16% of the isolates. Seven serovars were encountered during all eight quarters. Three of these serovars i.e. Arost/Aedgkih (IA-1, IA-2), BroptlBajk (IB-3, IB-6), BrpyustlBacejk (IB-1, IB-2) were the most prevalent in the overall study, accounting for 60% of the isolates during the first quarter of the study and 36% of the isolates during the last quarter. Fifty-seven percent of the patients were infected in Stockholm (endemic infection). The proportion of endemic isolates among the three most common serovars declined throughout the study period (77% during the first quarter; 47% during the last quarter). A total of 32 PhIGS-serovars were recognised among 80 PPNG strains. Only four of these 32 serovars were encountered during more than two quarters. Of 57 patients with PPNG strains and with geographical origin of the infection known, only seven (12%), all infected in Sweden, might have transmitted their infection further into the society. Conclusions-The decline in the total number of gonorrhoea cases seen in Stockholm during the study period, was due mainly to a decline of endemic isolates of the three most prevalent serovars. Results from contact tracing and serotyping indicated that PPNG infections acquired abroad seldom become established in the commumity. Serovar determination seems valuable mainly as a tool for surveillance whereby the introduction and circulation of gonococcal strains in the community can be pursued. (Genitourin Med 1994;70:256-261) Introduction The development of a reliable and well functioning classification system for Neisseria gonorrhoeae by using monoclonal antibodies against protein I, the major outer membrane protein, has provided us with a tool for interpreting gonorrhoea epidemiology at the community level.'~ In 1987, we started a two year project with the aim of "eradicating" endemic gonorrhoea in Stockholm. At that time the incidence of gonorrhoea in Sweden had been continuously decreasing since 1970, except for a minor peak in 1976. The Stockholm area accounted for about one third of all Swedish gonorrhoea cases, 5.4% of which were caused by betalactamase producing Neisseria gonorrhoeae (PPNG) strains. One object of the project was to characterise endemic versus non-endemic gonorrhoea in order to identify groups at risk for transmission of the infection. This would also include an evaluation of the effects of intensified contact tracing performed by specially trained social workers.7 Another object was to correlate antibiotic susceptibility, serovars, and auxotypes of the gonococcal isolates to geographical origin of the infection.8 The aim of the present study was to describe and analyse temporal changes in serovar patterns in the community to show the dynamics in the spread of Neisseria gonorrhoeae strains with special reference to PPNG strains. Methods The aim of the whole project was to eradicate endemic gonorrhoea from Stockholm. Endemic infection is therefore defined as infection acquired in Stockholm and non-endemic infection as infection acquired abroad (imported) or from other parts of Sweden. Study design The study group comprised all patients in Stockholm with culture proven gonorrhoea during the two year study period (October 1987-September 1989), diagnosed at any of the six bacteriological laboratories and with serologically classified gonococcal isolates. Strains from four patients were not serotyped and these patients were excluded. A patient returning within six weeks with a gonococcal isolate of identical serovar to that isolated on the first occasion and with no negative culture in between was only counted once. Our aim was to see all patients at one or other of the four venereal outpatient clinics in Department of Dermatovenereology, S6dersjukhuset, Stockholm, Sweden A-K Ruden Address correspondence to: Ann-Kerstin Ruden, Department of Dermatovenereology, Karolinska Institute, Sodersjukhuset S-1 18 83, Stockholm, Sweden. Accepted for publication 25 January 1994 256 group.bmj.com on October 18, 2017 Published by http://sti.bmj.com/ Downloaded from