Detection of Neisseria meningitidis in a paediatric patient with septic arthritis using multiplexed diagnostic PCR targeting meningitis/encephalitis (ME)

Donnchadh O’Sullivan, Barry Linnane, Amanda Mostyn, Nteimam Jonathan, Marie Lenihan, Nuala H. O’Connell, Colum P. Dunne

Neisseria meningitidis is associated with meningitis and septicemia. Septic meningococcal arthritis is relatively uncommon and its diagnosis associated with clinical and microbiological challenges. Early recognition and treatment is required to prevent joint destruction. We describe a case of an eleven-year-old boy with septic arthritis and the first reported use of a multiplexed diagnostic PCR test, capable of simultaneous rapid detection of 14 pathogens directly from CSF samples, to determine presence of N. meningitides in a synovial fluid sample. In this case, blood cultures and an aspiration of the joint fluid were negative for microbial growth, but leucocytes were present. Analysis of samples using the multiplexed FilmArray®meningitis/encephalitis panel (MEP) proved positive for N. meningitidis. In parallel, samples forwarded to an accredited reference laboratory confirmed the findings by bacterial 16S rRNA gene amplification and sequencing. Subsequent to these results, empiric treatment with intravenous flucloxacillin was discontinued and oral amoxicillin administered for 1 month. The status of the patient improved with etiology-based antimicrobial therapy. This case demonstrates difficulties associated with clinical and microbiological diagnosis of primary septic meningococcal arthritis. We describe the first successful use of the FilmArray®MEP assay in detection of N. meningitidis in that context.