A New Sequence Type of Neisseria meningitidis Serogroup C Associated With a 2016 Meningitis Outbreak in Mali

Abstract

In 2016, Mali reported a bacterial meningitis outbreak consisting of 39 suspected cases between epidemiologic weeks 9 and 17 with 15% case fatality ratio in the health district of Ouéléssebougou, 80 kilometers from the capital Bamako. Cerebrospinal fluid specimens from 29 cases were tested by culture and real-time polymerase chain reaction; 22 (76%) were positive for bacterial meningitis pathogens, 16 (73%) of which were Neisseria meningitidis (Nm). Of the Nm-positive specimens, 14 (88%) were N meningitidis serogroup C (NmC), 1 was NmW, and 1 was nongroupable. Eight NmC isolates recovered by culture from the outbreak were characterized using whole genome sequencing. Genomics analysis revealed that all 8 isolates belonged to a new sequence type (ST) 12446 of clonal complex 10217 that formed a distinct clade genetically similar to ST-10217, a NmC strain that recently caused large epidemics of meningitis in Niger and Nigeria. The emergence of a new ST of NmC associated with an outbreak in the African meningitis belt further highlights the need for continued molecular surveillance in the region.

Molecular characterization of Neisseria meningitidis isolates recovered from patients with invasive meningococcal disease in Colombia from 2013 to 2016

“…New STs may arise by horizontal gene transfer between circulating N . meningitidis strains and recombination events [ 37 ]. It is possible that clonal group ST-9493 is associated with the ST-41/44 cc or represents a new cc; however, additional genome analysis is required to more accurately reveal relationships among the strains.…”

“…ST-9493 was identified in isolates collected from patients in an outbreak of IMD in Colombia, related to ST-41/44 cc [12], and from patients in different regions of the country, demonstrating the local expansion of this ST. Several studies have shown the emergence of new STs of N. meningitidis serogroup B are associated with outbreaks or endemic disease, and it may be considered as a new meningococcal cc [34][35][36]. New STs may arise by horizontal gene transfer between circulating N. meningitidis strains and recombination events [37]. It is possible that clonal group ST-9493 is associated with the ST-41/44 cc or represents a new cc; however, additional genome analysis is required to more accurately reveal relationships among the strains.…”

Molecular insights into meningococcal carriage isolates from Burkina Faso 7 years after introduction of a serogroup A meningococcal conjugate vaccine

“…CC10217 is an emerging invasive CC that has already caused numerous outbreaks in the meningitis belt [5,6]. In our study, we identified carriage isolates belonging to this CC from three STs, two of which have been the cause of a recent outbreaks in Burkina Faso and in nearby countries such as Mali (ST-12446) [48], Niger and Nigeria (ST-10217) [6,49]. Our phylogenetic analysis revealed that the carriage and invasive isolates were genetically distinct; while carriage and invasive isolates belonging to the same ST were more closely related than to the other STs, they did not cluster together.…”

Meningococcal Meningitis Outbreaks in the African Meningitis Belt After Meningococcal Serogroup A Conjugate Vaccine Introduction, 2011–2017

“…Outbreaks at subdistrict level and in hard-to-reach areas may therefore have been missed, as well as small outbreaks not meeting the standard regional definition. This was likely the case of a reported outbreak in Mali, in 2017 [33], which was not included here as it did not cross the epidemic threshold as per ES data. Of note, the definition of outbreaks in the meningitis belt is derived from historical NmA epidemics and calculation of weekly attack rates at the district level.…”