Epidemiological and etiological characteristics of serogroup C and serogroup W135 Neisseria meningitidis in Hunan Province

Abstract:

ObjectiveTo understand epidemiological and etiological characteristics of serogroup C and W135 Neisseria meningitidis(Nm) in Hunan Province.MethodsNm strains isolated from blood or cerebrospinal fluid of patients with epidemic cerebrospinal meningitis, as well as throat swab specimens of close contacts of patients and healthy people in Hunan Province from 2006 to 2016 were collected, strains were performed biochemical testing and serological grouping. Partial strains of serogroup C and serogroup W135 were selected to perform antimicrobial susceptibility testing, and perform genotyping by pulsedfield gel electrophoresis (PFGE) and multilocus sequence typing (MLST), epidemiological characteristics were analyzed.ResultsAfter being confirmed by biochemical and serological detection, 22 strains of serogroup C Nm and 9 strains of serogroup W135 Nm were selected to perform antimicrobial susceptibility testing, results showed that all strains were sensitive to most detected antimicrobial agents, but serogroup C Nm were all resistant to compound sulfamethoxazole, resistance rate of serogroup W135 Nm was 55.56%, difference was statistically significant （χ2=7.61，P=0.006）. After PFGE typing, 22 strains of serogroup C Nm were divided into 5 PFGE bands, HNC01 band of 5 strains and HNC02 band of 13 strains were of the same subtype; PFGE band of first isolated strain of serogroup C in Hunan Province in 2006 was HNC02, which was identical with strains isolated from patients and close contacts of patients in 2012 and 2013, there was only one band that was different from band HNC01 in strains isolated from patients in 2008, 2010, and 2013, all were dominant bands. 9 strains of serogroup W135 Nm were divided into 2 band patterns after PFGE typing, the strain from the first patient was the same type as the strains isolated from patients in 2013 and 2016, all were HNW01 type. Dominant strains were selected for MLST, results showed that serogroup C Nm was ST4821 type, serogroup W135 was ST11 type, all were highly pathogenic clones of Nm.ConclusionAfter the first case of serogroup C and serogroup W135 epidemic meningitis appeared in Hunan Province, both became the dominant epidemic clone group of the disease, serogroup C Nm decreased in recent years, but new epidemic types have emerged. Serogroup W135 became new epidemic strain of epidemic cerebrospinal meningitis in this province since 2012, the dominant strain is consistent with the globally invasive serogroup W, which may cause a new pandemic, corresponding prevention and control policy should be formulated timely.