Genetic relationships among strains of Neisseria meningitidis causing disease in Italy, 1984-7.

Since 1984 a change in the epidemiological pattern of meningococcal disease in Italy has occurred with a predominance of Neisseria meningitidis of serogroup C (76%), serotype 2a and a high proportion of strains resistant to sulphonamides (71%). In order to understand better the epidemiology of the group C N. meningitidis strains responsible for the disease over the last years in Italy, we studied the genetic features of phenotypically closely related strains, by enzyme electrophoresis. The results showed that the genetic and the phenotypic characteristics of the 57 strains studied were similar, suggesting that spread of a single clone during recent years in our country. This result is in agreement with the circulation of strains typical of epidemic situations, despite the decreasing incidence of meningococcal disease in Italy.