Rapid sequence-based identification of gonococcal transmission clusters in a large metropolitan area.

In large metropolitan areas, which typically have the highest rates of gonorrhea, the identification of chains of transmission by use of partner notification is problematic, and there is an increasing interest in applying molecular approaches, which would require new discriminatory high-throughput procedures for recognizing clusters of indistinguishable gonococci, procedures that identify local chains of transmission. Sequencing of internal fragments of 2 highly polymorphic loci, from 436 isolates recovered in London during a 3-month period, identified clusters of antibiotic-resistant and antibiotic-susceptible isolates with indistinguishable genotypes, the vast majority of which were also identical or closely related by other methods, and defined groups of individuals who typically had similar demographic characteristics. This discriminatory sequence-based approach produces unambiguous data that easily can be compared via the Internet and appears to be suitable for the identification of linked cases of gonorrhea and the timely identification of transmission of antibiotic-resistant strains, even within large cities.