Objective To analyze 17 strains of Neisseria meningitidis isolated from meningococcal meningitis patients and close contacts in Liaoning province from 2006 to 2017, and understand the sequence type and molecular typing characteristics of N. meningitidis.

Methods The genetic evolution and clustering analysis of N. meningitidis strains were carried out by using multi locus sequential typing technique with the software Splits Tree and the method of eBURST.

Results There were 11 different ST types in 17 strains of N. meningitidis, including ST-5 complex/subgroup Ⅲ, ST-4821, ST-11 complex/ET-37 complex and unassigned complex STs. ST-5 complex/subgroup Ⅲ strains accounted for the highest proportion (about 47.06%, 8/17), 5 strains were from patients infected with N. meningitidis A and 3 strains were from close contacts and ST-7 was the main type. The clones of ST-4821 contained ST-4821 and ST-5664. ST-4821 strain was from a patient with N. meningitidis C in 2012, and ST-5644 strain was from a close contact of patients infected with N. meningitidis B in 2012. Only one strain was ST-11, which was from the close contact of patients infected with N. meningitidis W135 in 2009. There were 6 STs in the six serogroup B and non sero-groupable strains. The sequence type was diverse and there was no predominant sequence group. Among them, ST-12994 was the newly discovered ST type, which was from close contact in 2017.

Conclusion Multiple clone groups of N. meningitidis strain existed in Liaoning and the ST-5 complex/subgroup Ⅲ was the main clone group in serogroup A. The study results revealed the genetic evolution of N. meningitidis in Liaoning, also provided scientific evidence for the prevention and control of meningococcal meningitis.