Genetic and antigenic characteristics of Neisseria meningitidis strains isolated in the Czech Republic in 1997-1998

Strains of Neisseria meningitidis isolated from patients and asymptomatic i ndividuals who had been in contact with patients were investigated using fo ur typing methods with the aim of identifying any heterogeneity and/or homo geneity among the: strains. In 1993, a dramatic change in the incidence and severity of invasive meningococcal disease in the Czech Republic occurred as a consequence of the appearance of a Neisseria meningitidis strain of ph enotype C:2a:P1.5,2 and electrophoretic type ET-15, belonging to the ET-37 complex, which had not previously been identified in this country. Presente d here are the results of a study of the relationships between 58 Neisseria meningitidis isolates collected between January 1997 and June 1998. Forty- nine isolates originating from patients with invasive meningococcal disease and nine from healthy contacts were analyzed using the following four meth ods: whole-cell enzyme immunoassay, multilocus enzyme electrophoresis, puls ed-field gel electrophoresis, and randomly amplified polymorphic DNA analys is. A high prevalence of phenotype C:2a:P1.5,2 electrophoretic type ET-15 w as confirmed among the patients' strains. Nevertheless, during the study pe riod, they became heterogeneous. Strains isolated from healthy contacts sho wed greater heterogeneity in serological phenotypes and electrophoretic typ es from the beginning of the study, and electrophoretic type ET-15 strains were less frequent. Within the electrophoretic type ET-15 clone, strains sh owing the identical serological phenotype (with the exception of one isolat e) were indistinguishable using randomly amplified polymorphic DNA analysis , while pulsed-field gel electrophoresis revealed heterogeneity with 12 pul sed-field gel electrophoretic types identified. The strains from the same c luster displaying the same serological phenotype were indistinguishable wit h any of the methods used.