Objectives: To analyze clinical meningococcal strains associated with meningococcal septic arthritis cases in England and Wales, and to identify associations between patient age, the synovial joint affected and strain characteristics. Methods: IMD cases confirmed by the Meningococcal Reference Unit (UK Health Security Agency) between January 2010 and December 2020 were included in the analysis. Septic arthritis cases were defined as those featuring detection and/or isolation of N. meningitidis from an articular site. Capsular grouping was performed by serology on clinical isolates and/or real-time PCR on clinical samples. Results: We identified 162 cases of meningococcal septic arthritis, representing 2% of all invasive meningococcal disease cases during the study period. The knee and the hip were the most commonly affected joints, with the former significantly more frequent in adults and the latter seen more commonly in children and adolescents. Group B strains were between 2 and 6 times less likely to cause septic arthritis in relation to groups W, C and Y strains. Conclusions: Meningococcal septic arthritis remains a rare manifestation of invasive meningococcal disease. Strain and age associations identified in this study remain unexplained. Future analyzes including clinical case information may help to explain these findings.
Bibliographical noteFunding Information:
The authors would like to acknowledge all the laboratories that submitted samples to the MRU and the UKHSA Health Protection Teams that have provided additional case details, without whom, this analysis could not have been performed.
This study was funded by UK Health Security Agency. No external funding or specific grants were obtained.