Diagnostic accuracy of two multiplex real-time polymerase chain reaction assays for the diagnosis of meningitis in children in a resource-limited setting

Abstract

Introduction: Accurate etiological diagnosis of meningitis is important, but difficult in resource-limited settings due to prior administration of antibiotics and lack of viral diagnostics. We aimed to develop and validate 2 real-time multiplex PCR (RT-PCR) assays for the detection of common causes of community-acquired bacterial and viral meningitis in South African children.

Methods: We developed 2 multiplex RT- PCRs for detection of S. pneumoniae, N. meningitidis, H. influenzae, enteroviruses, mumps virus and herpes simplex virus. We tested residual CSF samples from children presenting to a local paediatric hospital over a one-year period, whose CSF showed an abnormal cell count. Results were compared with routine diagnostic tests and the final discharge diagnosis. We calculated accuracy of the bacterial RT-PCR assay compared to CSF culture and using World Health Organisation definitions of laboratory-confirmed bacterial meningitis.

Results: From 292 samples, bacterial DNA was detected in 12 (4.1%) and viral nucleic acids in 94 (32%). Compared to CSF culture, the sensitivity and specificity of the bacterial RT-PCR was 100% and 97.2% with complete agreement in organism identification. None of the cases positive by viral RT-PCR had a bacterial cause confirmed on CSF culture. Only 9/90 (10%) of patients diagnosed clinically as bacterial meningitis or partially treated bacterial meningitis tested positive with the bacterial RT-PCR.

Discussion: In this population the use of 2 multiplex RT-PCRs targeting 6 common pathogens gave promising results. If introduced into routine diagnostic testing, these multiplex RT-PCR assays would supplement other diagnostic tests, and have the potential to limit unnecessary antibiotic therapy and hospitalisation.

Fig 1. Flowchart showing results of bacterial multiplex realtime-PCR compared to cerebrospinal fluid microscopy and culture.

Fig 2. Results of bacterial and viral multiplex realtime PCR assays in cases of suspected meningitis in children presenting to the acute care or outpatient departments of the Red Cross War Memorial Children’s Hospital in Cape Town, South Africa, November 2012–October 2013 (n = 292).

Fig 3. Monthly variation in detection of selected pathogens using bacterial and viral multiplex realtime PCR assays, in cases of suspected meningitis in children presenting to the acute care or outpatient departments of the Red Cross War Memorial Children’s Hospital in Cape Town, South Africa, November 2012–October 2013 (n = 292).