Abstract
Since 2015, the incidence of invasive meningococcal disease (IMD) caused by serogroup W (MenW) has increased in Sweden, due to the introduction of the 2013 strain belonging to clonal complex 11. The aim of this study was to describe the clinical presentation of MenW infections, in particular the 2013 strain, including genetic associations. Medical records of confirmed MenW IMD cases in Sweden during the years 1995-2019 (n = 113) were retrospectively reviewed and the clinical data analysed according to strain. Of all MenW patients, bacteraemia without the focus of infection was seen in 44%, bacteraemic pneumonia in 26%, meningitis in 13% and epiglottitis in 8%, gastrointestinal symptoms in 48% and 4% presented with petechiae. Phylogenetic analysis was used for possible links between genetic relationship and clinical picture. The 2013 strain infections, particularly in one cluster, were associated with more severe disease compared with other MenW infections. The patients with 2013 strain infections (n = 68) were older (52 years vs. 25 years for other strains), presented more often with diarrhoea as an atypical presentation (P = 0.045) and were more frequently admitted for intensive care (P = 0.032). There is a risk that the atypical clinical presentation of MenW infections, with predominantly gastrointestinal or respiratory symptoms rather than neck stiffness or petechiae, may lead to delay in life-saving treatment.
Highlights
Neisseria meningitidis is a strictly human pathogen and the causative agent of invasive meningococcal disease (IMD), which classically presents as septicaemia with or without meningitis
We analysed the clinical presentation of 2013 strain infections compared with other MenW isolates, and we interpret that the 2013 strain may cause more severe disease
The need for intensive care was high, both for all patients (55%) and for the 2013 strain (62%) cohort, which is more than previously described for MenW infections [13, 14]
Summary
Neisseria meningitidis is a strictly human pathogen and the causative agent of invasive meningococcal disease (IMD), which classically presents as septicaemia with or without meningitis. One reason for the increased incidence of MenW infections is the introduction and spread of a particular strain, the ‘2013 strain’ (which is referred to as the ‘novel UK strain’ or the ‘UK 2013 strain’) named after the year of its first appearance in the UK [9, 10]. This strain belongs to clonal complex 11 (cc11), is part of the MenW cc South American substrain and features the fine type PorA subtype P1.5,2,36-2 and FetA F1-1 [10]. Since 2015, the 2013 strain is the most common individual strain causing IMD in Sweden
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