Abstract
Serogroup A Neisseria meningitidis has repeatedly caused epidemics of invasive meningococcal disease (IMD) in developing nations since the 1960s. The present study is the first detailed study of serogroup A bacteria isolated in Canada. Thirty-four serogroup A meningococcal isolates collected from individuals with IMD in Canada between 1979 and 2006 were characterized by serology and multilocus sequence typing of seven housekeeping enzyme genes and genes encoding three outer membrane protein antigens. Isolates were assigned to either the sequence type (ST)-1 or the ST-5 clonal complex. Clones within the ST-1 complex were recovered between 1979 and 1992, while clones of the ST-5 complex were isolated between 1987 and 2006; respectively, they accounted for 70.6% and 29.4% of all isolates studied. Isolates of the ST-1 complex were characterized by serosubtype antigen P1.3 or P1.3,6 with PorB allele 60 (serotype 4) and FetA sequence F5-1, while isolates of the ST-5 complex were characterized by serosubtype antigen P1.9 with PorB allele 47 (also serotype 4) and FetA sequence F3-1. The Canadian serogroup A IMD isolates likely originated in travellers returning from hyperendemic or epidemic areas of the globe where serogroup A bacteria circulate. Although the Canadian cases of serogroup A IMD were caused by clones known to have caused epidemics in developing countries, disease incidence remained low in Canada.
Highlights
Serogroup A Neisseria meningitidis has repeatedly caused epidemics of invasive meningococcal disease (IMD) in developing nations since the 1960s
The present study examines serogroup A N meningitidis isolates collected from individuals with IMD in Canada over a 28-year time span
Case characteristics of serogroup A meningococci collected in Canada between 1979 and 2006 Of the 70 invasive serogroup A meningococcal isolates submitted to the National Microbiology Laboratory (NML) by provincial laboratories between 1979 and 2006, most were from the year 1979, with much lower numbers seen in later years (Figure 1)
Summary
Serogroup A Neisseria meningitidis has repeatedly caused epidemics of invasive meningococcal disease (IMD) in developing nations since the 1960s. MÉTHODOLOGIE : Trente-quatre isolats de méningocoque de sérogroupe A prélevés chez des personnes atteintes de MMI au Canada entre 1979 et 2006 ont été caractérisés par sérologie et typage séquentiel multilocus de sept gènes enzymatiques domestiques et gènes codant trois antigènes protéiques de la membrane externe. Les isolats du complexe TS-1 se caractérisaient par les sous-sérotypes des antigènes P1.3 ou P1.3,6 avec l’allèle 60 PorB (sérotype 4) et la séquence F5-1 FetA, tandis que les isolats du complexe TS-5 se caractérisaient par le sous-sérotype de l’antigène P1.9 avec l’allèle 47 PorB (également le sérotype 4) et la séquence F3-1 FetA, CONCLUSIONS : Selon toute probabilité, les isolats canadiens de MII de sérogroupe A provenaient de voyageurs de retour d’une région hyperendémique ou épidémique du monde, où circulent les bactéries de sérogroupe A. Même si les cas canadiens de MII de sérogroupe A étaient causés par des clones responsables d’épidémies dans les pays en voie de développement, l’incidence de la maladie demeurait faible au Canada
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