OBJECTIVETo study the characteristics of epidemiology and molecular typing on Neisseria meningitidis serogroup C strains associated with outbreaks of Anhui province and sporadic cases in China, using pulsed field gel electrophoresis (PFGE).

METHODS212 Neisseria meningitidis serogroup C strains were isolated from invasive meningococcal cases, close contacts and healthy carriers, including 48 strains from Anhui province with 38 strains associated with serogroup C outbreaks. PFGE were performed by genomic DNA digestion with Nhe I restriction enzyme. The results of PFGE were analyzed by BioNumerics software (Version 4.0, Applied Maths BVBA, Belgium).

RESULTSA total number of 212 Neisseria meningitidis serogroup C isolates were typed by 43 patterns, named AH1 to AH43. In China, AH1 pattern was the major PFGE pattern with 69.3% (n = 147) of all strains, distributed in 11 provinces. Three types of PFGE patterns (AH1 to AH3) were found in 48 strains from Anhui province, in which, 93.8% (n = 45) belonged to AH1. 97.4% (n = 37) of 38 strains associated with serogroup C outbreaks in Anhui province showed AH1 pattern. A total of 53 serogroup C strains were isolated from invasive meningococcal cases with 67.9% (36/53) of AH pattern. 71.9% (87/121) of serogroup C strains isolated from contacts of invasive meningococcal cases was AH1 pattern and 63.2% (24/38) of the strains from healthy carriers showed AH1 pattern.

CONCLUSIONBy PFGE typing and analysis, AH1 pattern of Neisseria meningitidis serogroup C strains was proved to be the main clone which causing the outbreaks in Anhui province and might be responsible for the sporadic serogroup C meningococcal disease epidemics else where in the country.