Phenotypic and genetic characterization of a unique variant of serogroup C ET-15 meningococci (with the antigenic formula C:2a:P1.7,1) causing invasive meningococcal disease in Quebec, Canada.

Abstract

Serogroup C Neisseria meningitidis belonging to the electrophoretic type (ET) ET-15, a variant of ET-37, is endemic in Canada. Like other serogroup C ET-37 meningococci, the endemic ET-15 strains are usually found to carry the serotype and serosubtype antigens of 2a:P1.5,2. In 2001, a sudden increase in the number of cases of serogroup C meningococcal disease in Quebec, Canada, was caused by an antigenic variant of the ET-15 strain. This antigenic variant carries the unique serosubtype marker of P1.7,1. Strains of C:2a:P1.7,1 meningococci were not isolated in Canada in large numbers prior to 2001, and the characteristics of these meningococcal strains linked to an outbreak in Quebec, Canada, are described in the present study.