To the editor: The serogroups of Neisseria meningitidis (N. meningitidis) strains are distributed with distinct regional characteristic.1 Historically, meningococcal diseases in China have mainly been caused by serogroup A.2 Since the outbreaks in the Anhui province in 2003 and 2004, N. meningitidis serogroups A and C have become the major causative agents for most meningococcal diseases and most of serogroup A/serogroup C isolates belong to the ST-7/ST4821 complex, respectively.3 Strains of the serogroup C belonging to the ST-11/ET37 clonal complex which is prevalent in North America, Europe and Africa had previously not been observed in China. However, an isolate from a Kuwaiti case that resulted in the patient's death was identified as serogroup C ST-11/ET37 N. meningitidis clonal complex in July, 2011, in Beijing. This is the first ST-11clonal complex serogroup C N. Meningitidis strain in China.
A suspected strain was isolated from blood specimens of a 23-year-old male Kuwaiti dead case in July, 2011 and was identified as N. meningitidis serogroup C by bacteriology and serology. The realtime PCR data supported the results. Further investigated this N. meningitidis strain by multilocus sequence typing (MLST) of the variable regions of the genes (porA, porB and fetA) encoding the outer membrane proteins. The allele numbers for abcZ, adk, fumC, gdh, pdhC, aroE and pgm were 10, 3, 3, 8, 4, 4 and 6, respectively. This strain belonged to the ST-11 (ST-11/ET37 complex). The PorA genotype of the strain was determined to be VR1 P5-1, VR2 P10-8, which was a genotype associated with the ST-11 strains. The porB and fetA alleles of this strain were 1 and F3-6, respectively.
In China, most monitored serogroup C strains were ST4821.3 The serogroup C isolate reported in this case has a phenotype C:1:P1. 5-1, 10-8 of the ST-11 clonal complex, which differs from other strains detected. This is the first ST-11 clonal complex serogroup C N. meningitidis strain in China. ST-11 clonal complex belongs to the “hyperinvasive lineages”, and appears to have an increased propensity to cause invasive disease.4 Most serogroup C meningococci recovered in North America, Europe, and Africa belong to the ST-11 clonal complex, which is known to cause both endemic and pandemic disease in different parts of the world.1
C serogroup ST-11 strains had never been surveyed before in China and no strains of N. meningitidis were isolated from throat swabs collected from 3 close contacts of this patient. Some studies demonstrated that the commensal association of particular N. meningitidis clones with a host is a long-term relationship, with 90% of carriers keeping the same clone for at least 5-6 months. Nevertheless, hypervirulent clones vary greatly in their capability to establish a commensal relationship with their host, the strains of the ST-11 complex being especially poor colonizers.5 Thus, we deduced that the isolate from this patient was likely imported. It will be disastrous if an outbreak of this serotype of meningcoccal disease occurs in China, since it is not clear whether the vaccines in routine use elict protective immunity enough.
Antimicrobial susceptibility tests by antimicrobial gradient strips showed that except for intermediate susceptible to ampicillin, the strain isolated from the patient respond to the most frequently used therapeutic and prophylaxis agents.
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by analysis of restriction fragment length polymorphisms in the gene encoding the class 1 outer membrane protein: application to assessment of epidemics throughout the last 4 decades in China. J Clin Microbiol 1995; 33: 458-462.
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