Performance characteristics of the polymerase chain reaction assay to confirm clinical meningococcal disease

Background-Confirmation of clinical meningococcal disease (MCD) is essentia l for management of patients, contacts, and outbreaks. Blood and CSF cultur es, the traditional gold standard diagnostic tests, have been adversely aff ected by preadmission parenteral penicillin and fewer lumbar punctures. Rap id, reliable serogroup determination without the need to grow isolates coul d improve laboratory confirmation of MCD. Aims-To determine performance characteristics of the currently available me ningococcal polymerase chain reaction (PCR) assays in a clinical setting. Methods-Prospective study of 319 children presenting with a suspected diagn osis of MCD (fever and a rash, or suspected bacterial meningitis) over a 16 month period. Results-A total of 166 (52% of all) children had clinical MCD: diagnosis wa s confirmed microbiologically in 119 (72%) of these. Performance characteri stics (sensitivity, specificity, negative predictive value, positive predic tive value) in confirmation of clinical MCD were respectively (95% confiden ce interval): blood culture 31% (24-38%), 100%, 57% (49-65%), 100%; blood P CR 47% (39-55%), 100%, 65% (58-73%), 100%; any test positive 72% (65-79%), 100%, 77% (70-84%), 100%. Conclusions-Meningococcal DNA detection in blood or CSF by PCR is a useful method of diagnosis of MCD. PCR of peripheral blood performs better than bl ood culture. In a child with clinically suspected MCD, PCR assays, bacteria l antigen tests, and oropharyngeal swabbing for meningococcal carriage shou ld be performed in addition to blood or CSF culture, to improve case confir mation.