Pulsed-Field Gel Electrophoresis as an Epidemiologic Tool for Neisseria gonorrhoeae

Abstract
The increasing incidence of gonorrhea in Sweden in 1998 was due to mostly domestic cases. Among these, two core groups were identified: homosexual men with serovar IB-2 and young heterosexuals with serovar IB-3. To explore the genetic homogeneity/heterogeneity within the predominant serovars, IB-2 and IB-3, of Neisseria gonorrhoeae in Sweden by pulsed-field gel electrophoresis (PFGE) and to compare these results to epidemiologic information, as well as examine the genetic diversity within and between the 25 other represented serovars of N gonorrhoeae. By PFGE, 237 N gonorrhoeae isolates were examined, and the results were compared with epidemiologic data for the IB-2 and IB-3 isolates. In 79% of the domestic IB-2 cases involving homosexuals and 66% of the domestic IB-3 cases involving young heterosexuals, the isolates were genetically indistinguishable by PFGE. A high genetic diversity was identified within and between the 27 included serovars. Examination by means of PFGE indicated that one N gonorrhoeae clone each of the serovars IB-2 and IB-3 created the majority of the two core groups of domestic cases.