The epidemiology of gonococcal serovars in Edinburgh 1990-1993
With the advent of gonococcal stereotyping many areas have reported wide differences in their prevalence of different strains of infection. This study was designed in an attempt to correlate a variety of clinical markers of infection and characteristics of the organism with the observed serovar pattern. All patients with a laboratory diagnosis of gonorrhoea in Edinburgh between January 1990 and December 1993, most of whom attended the Genitourinary Medicine clinic, were included in the study. For comparison a more limited analysis was also performed on patients attending Genitourinary Medicine clinics and gonorrhoea in Glasgow between 1990 and 1992, Aberdeen in 1992 and Newcastle in 1992. 508 patients infected with 23 different serovars were seen over the 4 year period in Edinburgh. The commonest serovars isolated in Edinburgh were 1A-2, 1A,-6, 1A-16, 1B-1, 1B-2, 1B-3, 1B-6 and 1B-7 accounting for 88% of all infections. As predicted each of the four areas demonstrated differing serovar patterns with a small number of common serovars accounting for the majority of infections and larger number of serovars which were only isolated infrequently. A number of factors appeared to influence the variation in serovars: antibiotic resistance, serovar mutation, sexual mixing patterns, and immune response to infection and asymptomatic strains of infection. Although individual factors do not have a marked influence on the pattern of gonococcal serovars in Edinburgh they may act in combination with the background selective pressures within the environment. Sexual mixing patterns, which are difficult to measure, make determining the relative role of each individual factor inaccurate.