Molecular characteristics of invasive Neisseria meningitidis isolated in Beijing, 2005–2016

Objective To understand the molecular characteristics of invasive Neisseria meningitidis strains isolated from patients in Beijing from 2005 to 2016.

Methods After biochemical identification, the serogroups of 24 N. meningitidis strains from the patients in Beijing, 2005–2016, were detected with slide agglutination test. Real time fluorescence quantitative PCR was conducted to identify the genogroups of all theN. meningitidis strains and 4 nucleic acid positive samples. Multi locus-sequence typing (MLST) was done for the sequence typing of the 28 N. meningitidis samples, and porA and fetA typing were conducted too.

Results N. meningitidis A, B and C were predominant during the past 12 years. All the 16 samples detected before 2009 were N. meningitidis A and C positive, all the 12 samples detected after 2009 wereC and B positive. The sequence type of all N. meningitidis A strains belonged to ST-5 clonal complex, porA P1.20, 9 was only found in ST-7 and the fetA types of all N. meningitidis A strains were F3-1. ST-4821 clonal complex was predominant in N. meningitidis C strains, which had P1.12-1, 16-8, P1.7-2, 14, P1.20, 23-7 and the fetA types of all N. meningitidis C strains were F3-3. The sequence types of N. meningitides B were complex and dispersed.

Conclusion The predominant invasive N. meningitidis in Beijing characterizes by A: P1.20, 9, F3-1:ST-5 (ST-5 clonal complex) and C:P.12-1, F3-3:ST-4821 (ST-4821 clonal complex). The trend of obvious decrease ofN. meningitidis A and increase of N. meningitidis B is observed, suggesting that the predominant invasive N. meningitidishas changed over time. It is necessary to strengthen the molecular epidemiological surveillance for N. meningitidis, especially N. meningitidis B to which no vaccine is available.