Epidemiological value of lipopolysaccharide and heat-modifiable outer-membrane protein serotyping of group-A strains of Neisseria meningitidis.

The lipopolysaccharide (LPS) and heat-modifiable outer-membrane protein (P') serotypes of 39 coded strains of group-A Neisseria meningitidis isolated from patients during seven geographically and temporally separate outbreaks of infection were determined blindly. LPS serotype discriminated between strains from different outbreaks and between strains of differing sulphadiazine sensitivity within a single outbreak. Thirty-seven strains were of three separate serotypes and no strain was of multiple serotypes. In contrast, P' serotypes did not discriminate between strains. Multiple serotypes for single strains and among strains from a single outbreak were the rule. LPS serotyping appears to be a useful epidemiological tool for distinguishing group-A strains of N. meningitidis.