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

Increasing incidence of meningococcal disease in Spain associated with a new variant of serogroup C

Serogroup B has been the main cause of meningococcal disease in Spain since at least 1979, but in recent years an increase in the prevalence of infection due to serogroup C meningococci has been detected. In 1996, for the first time, most cases of meningococcal disease were caused by serogroup C strains. The sero/subtype of all serogroup C meningococci received from 1993 to June 1996 was determined, and the results showed that C:2b:P1.2,5, the most common phenotype in 1995 and 1996 (63% and 65%, respectively), represented only 4.8% of strains in 1993. The C:2b: P1.2,5 epidemic strains appear to be responsible for the high prevalence of serogroup C in Spain. One hundred fifty-one randomly selected serogroup C strains were analyzed by multilocus enzyme electrophoresis, ribotyping, and pulsed-field gel electrophoresis. Pulsed-field gel electrophoresis provided the most accurate information: more than 80% of the C:2b:P1.2,5 and C:2b:P1.2 isolates exhibited one of two very closely related profiles, while most of the C:2b:NST and C:2b:P1.5 strains had a pattern located at a genetic distance of 0.24 from those two profiles. The results show that C:2b:P1.2,5 strains represent a subclone or a genetic variant of the previously identified Spanish epidemic clone C:2b:non-subtypable strains.

Molecular epidemiology of recent United Kingdom isolates of Neisseria meningitidis serogroup C

The genomes of 34 recent United Kingdom isolates of Neisseria meningitidis serogroup C were examined by restriction enzyme digestion and by conventional and pulsed-field gel electrophoresis (PFGE). Strains were assigned to groups on the basis of the Dice similarity coefficient; strains with values of > 92% were considered to be clonally related. Twelve clones were identified by PFGE. Strains of two clonal groups predominated. Restriction endonuclease analyses using the 'high frequency cleavage' endonuclease Stu I and conventional electrophoresis gave 11 groups; in general it had lower resolving power than PFGE.

Emergence of a virulent clone of Neisseria meningitidis serotype 2a that is associated with meningococcal group C disease in Canada

Multilocus enzyme electrophoresis was used to characterize 378 isolates of Neisseria meningitidis serogroup C recovered during a period of an increase in group C meningococcal disease in Canada. Thirty-four enzyme electrophoretic types were found among the isolates, which were predominantly (96.0%) serotype 2a. One clone (ET 15), characterized by a rarely occurring allele for the enzyme fumarase, was responsible for a focal outbreak in Ontario followed by the spread of group C disease across the province. This clone, which occurred infrequently among strains isolated in 1986, accounted for over 65% of group C strains associated with meningococcal disease in Canada in 1990.