Multilocus sequence typing of Neisseria meningitidis strains isolated in Hainan province

Objective To assess molecular characteristics of Neisseria meningitidis (Nm)strains isolated in Hainan province.Methods Multilocus sequence typing(MLST)technique was used to analyze 17 Nm strains isolated from epidemic cerebrospinal meningitis (ECM) patients,contactors and healthy carriers in Hainan province between 2005 and 2015.Results The 17 isolates were categorized into 11 different sequence types (STs) belonging to ST-4821,ST-11,ST-5,ST-175,ST-364 clonal complex,and 5 unassigned clonal complexes.Among the 11 clonal complexes,ST-4821,ST-11,and ST-5 belongs to highly pathogenic clonal cluster,accounting for 29.41%(5/17),17.65%(3/17),and 5.88% (1/17) of all isolated strains.The ST-4821 clonal complex was identified with ST-4821 and ST-3200 STs,the former was isolated from three ECM cases of group C and a close contact of an unserotyped case and the latter was isolated from healthy carriers of Nm serogroup C in 2005.The ST-11 and ST-5 clonal complex were isolated from healthy carriers of Nm serogroup W135 of STs 11 and unserotyped Nm of ST-7.The 5 isolated strains of serogroup B presented 5 different STs (ST-7962,ST-8209,ST-5615,ST-11127,and ST-11134),of which,ST-11127 and ST-11134 were newly identified STs;the strain with STs of ST-7962 isolated from one patient in 2015 and the strain of ST-11127 isolated from a close contact of ECM in 2010 were homological and belonging to unassigned complex sequence types.The strains with other sequence types showed no close evolutionary relationship with each other.Conclusion The molecular sequence types of Nm isolated in Hainan province are diverse.ST-4821 clonal complex is a predominant sequence type in Hainan province.Highly pathogenic Nm strains are prevalent in healthy population of Hainan province.