Randomly Amplified Polymorphic DNA Genotyping of Serogroup A Meningococci Yields Results Similar to Those Obtained by Multilocus Enzyme Electrophoresis and Reveals New Genotypes

Randomly amplified polymorphic DNA (RAPD) genotyping was applied to one representative strain of each of the 84 electrophoretic types (ETs) of Neisseria meningitidis serogroup A previously defined by multilocus enzyme electrophoresis (MEE) (J.-F. Wang et al., Infect. Immun. 60:5267‐5282, 1992). Twenty-seven additional isolates comprising six ETs were also tested. MEE and RAPD genotyping yielded similar dendrograms at the subgroup level. Similar results were obtained by both methods for 18 serogroup A meningococci isolated in The Netherlands between 1989 and 1993. Ten of these isolates defined a new subgroup, designated subgroup IX. One isolate belonged to the ET-5 complex, normally associated with serogroup B strains (D. A. Caugant et al., Proc. Natl. Acad. Sci. USA 83:4927‐4931, 1986). By RAPD genotyping, meningococci can be linked to previously characterized genotypes by using a computerized database, and dendrograms based on cluster analyses can easily be generated. RAPD analysis offers advantages over MEE since intermediate numbers of isolates of serogroup A meningococci can quickly be assigned to known subgroups and new subgroups can be defined. Neisseria meningitidis is an encapsulated gram-negative bacterium that causes meningitis and septicemia worldwide. Classification according to capsule polysaccharide type revealed 11 capsule types. Serogroup A, B, and C isolates are the causes of about 90% of the cases of meningitis (13). Serogroup A strains are the leading cause of epidemics, whereas serogroup B and C strains generally cause endemic cases of infection and small outbreaks. Since World War II, large epidemics caused by