Genetic diversity of Neisseria meningitidis strains isolated in Rio de Janeiro, Brazil, evaluated by multilocus enzyme electrophoresis

AIMS: To analyse Neisseria meningitidis isolates from meningococcal meningitis cases in Rio de Janeiro (Brazil) from 1990 to 1993 and 1999-2002, to determine the genetic and relatedness with hypervirulent and epidemic strains. METHODS AND RESULTS: The isolates were analysed by multilocus enzyme electrophoresis (MEE) clustering into 83 electrophoretic types (ET). All isolates from 1999 to 2002, formed a cluster which included one strain of the ET-5 complex worldwide associated with epidemics. CONCLUSIONS: The overall results suggested a panmictic structure probably because of recombination events. The observation of a separated cluster including isolates from 1999 to 2002 and an ET-5 complex strain, also suggested the introduction of strains genetically related with this hypervirulent complex in the State of Rio de Janeiro (Brazil) over the last 5 years. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of strains related to the ET-5 complex in several states of Brazil was already described elsewhere, but this is the first time it was reported in the State of Rio de Janeiro. Our findings reinforce the necessity to genetically determine the clones which should be considered to produce a national vaccine against meningococcal meningitis.