Characterization of Neisseria meningitidis serogroup A strains from an outbreak in France by serotype, serosubtype, multilocus enzyme genotype and outer membrane protein pattern.

In an attempt to determine the epidemiological relationship between cases of infection caused by Neisseria meningitidis serogroup A in France between August 1987 and December 1988, and an outbreak which occurred in Mecca in August 1987, markers such as serotype, serosubtype, multilocus enzyme genotype and outer membrane protein (OMP) pattern were used to characterize the bacterial isolates. From a total of 28 cases, 20 strains were isolated. Sixteen isolates, including one which undoubtedly originated from the Mecca epidemic, were homogenous (serotype 4, serosubtype P1.9, multilocus enzyme genotype of clone III-1, identical OMP pattern). Four isolates had a different OMP pattern with little or no P1 protein, no P4 and no P6. Two of these isolates belonged to other clones (I.1 and group I) and they were considered to be unrelated to the Mecca epidemic strains. The origin of the remaining two isolates was not clear. It is concluded that the majority of the Neisseria meningitidis serogroup A strains recently isolated in France originate from the Mecca epidemic.