Characterisation of Neisseria meningitidis B causing invasive disease in the Czech Republic

Abstract number: 1732_318

Kriz P., Kalmusova J., Musilek M., Felsberg J., Haugvicova R., Caugant D., Jolley K., Maiden M.

Objectives: Invasive meningococcal disease (IMD) caused by Neisseria meningitidis B is endemic in the Czech Republic and its long-term incidence is stable (0.5/100,000 population), reaching peaks in the youngest age groups (up to 22.6/100,000 for 0–11 months olds and 2.7/100,000 for 1–4 years olds). The aim of this study was to characterise N. meningitidis B isolates from IMD and to assess the coverage of vaccines against N. meningitidis B.

Methods: The total number of N. meningitidis B isolated from IMD in the Czech Republic in the period 1993–2006 (Nov. 8) was 474. In all isolates serogrouping and sero/subtyping was performed. Subtyping by Whole Cell ELISA (WCE) was replaced by PorA sequencing recently (http://neisseria.org/nm/typing/). Sequence types (STs) were identified by multilocus sequence typing (MLST) in accordance with the MLST website (http://pubmlst.org/neisseria/). The number of N. meningitidis B IMD isolates investigated by MLST was 366.

Results: Sero/subtyping showed high heterogeneity: among 474 isolates, 88 phenotypes were found. The most frequent phenotype was B:4:P1.15 (15.4%), followed by B:15:P1.7,16 (8.2%) and B:15:P1.5 (5.7%). 15.4% of isolates were not typeable/subtypeable by WCE. PorA sequencing of these isolates further identified their heterogeneity. MLST confirmed this high heterogeneity: 142 STs, belonging to 16 clonal complexes, which represent 79.2% of isolates. There were three prevailing complexes: ST-18 complex (19.1%), ST-32 complex (18.8%) and ST-41/44 complex (16.9%). The Czech N. meningitidis B population is different compared to western Europe: 109 of the STs (76.8% of STs) and one clonal complex (ST-292 complex) were described for the first time in the Czech N. meningitidis B isolates. Coverage of sero/subtypes by currently being developped vaccines against N. meningitidis B is low (maximum 44.5% for nine-valent meningococcal B PorA vaccine).

Conclusion: Detailed characterisation of N. meningitidis B isolates from IMD in the Czech Republic in the period 1993–2006 showed their high heterogeneity and low coverage by currently available vaccines against N. meningitidis B.

Acknowledgement: This work was supported by Ministry of Health, by research grant 1A/8688–3/2005 of the Internal Grant Agency of Ministry of Health of the Czech Republic and made use of the Multi Locus Sequence Typing website (http://pubmlst.org/neisseria/) sited at the University of Oxford and funded by the Wellcome Trust and European Union.