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Cluster analysis of Neisseria meningitidis type 22 strains isolated in Poland
W Grzybowska1, S Tyski, L Berthelsen
1Department of Antibiotics and Microbiology, Drug Institute, Warsaw, Poland.
Abstract:
The aim of this study was to investigate the genetic relationships among strains belonging to Neisseria meningitidis serotype 22 recovered in Poland from 1995 to 1998. Phenotypical characterisation of meningococcal strains isolated from patients with meningococcal disease has been performed since 1995. Strains belonging to Neisseria meningitidis type 22 were most frequently recovered from severe cases of meningitis and septicaemia. The type 22 strains were separated into clusters by serosubtyping and DNA analyses by pulsed-field gel electrophoresis and ribotyping. However, the grouping according to serosubtypes was quite different from that obtained by ribotyping and pulsed-field gel electrophoresis. Furthermore, the two genotyping methods seldom identified the same clusters, nor were clusters identified among 26 Neisseria meningitidis type 22 strains recovered from patients hospitalised in five cities. Determination of the susceptibility to penicillin showed that a single strain was resistant (MIC, 2 mg/l) and that one-third (24/71) of the strains tested had reduced susceptibility (MIC range, 0.1-1 mg/l).
Insights
Genetic analysis of Neisseria meningitidis serotype 22 strains in Poland revealed distinct groupings via serosubtyping and genotyping. Penicillin susceptibility testing showed some strains had reduced or resistant profiles.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Neisseria meningitidis serotype 22 strains were frequently isolated from severe meningitis and septicaemia cases in Poland between 1995 and 1998.
- Phenotypic characterization of meningococcal strains has been conducted since 1995.
Purpose of the Study:
- To investigate the genetic relationships among Neisseria meningitidis serotype 22 strains recovered in Poland.
- To compare different genotyping methods for clustering these strains.
Main Methods:
- Serosubtyping of Neisseria meningitidis strains.
- DNA analysis using pulsed-field gel electrophoresis (PFGE) and ribotyping.
- Determination of penicillin susceptibility (Minimum Inhibitory Concentration - MIC).
Main Results:
- Serosubtyping produced different strain groupings compared to PFGE and ribotyping.
- PFGE and ribotyping seldom identified the same clusters.
- No distinct clusters were identified among strains from five different cities.
- One Neisseria meningitidis strain showed penicillin resistance (MIC, 2 mg/l), and one-third exhibited reduced susceptibility (MIC range, 0.1-1 mg/l).
Conclusions:
- Serosubtyping and molecular genotyping methods (PFGE, ribotyping) provide disparate views of Neisseria meningitidis serotype 22 genetic relatedness.
- The genetic diversity and penicillin susceptibility patterns of these strains warrant further investigation.