PCR OF PERIPHERAL-BLOOD FOR DIAGNOSIS OF MENINGOCOCCAL DISEASE

Meningococcal disease is normally suspected on clinical grounds and is confirmed by isolation of Neisseria meningitidis bacteria from blood or cerebrospinal fluid or, more recently, by serology or PCR of cerebr ospinal fluid. Achieving confirmation of a clinical diagnosis of menin gococcal disease has become more difficult in the last few years. The prehospitalization administration of parenteral benzylpenicillin norma lly renders blood cultures sterile, and lumbar puncture is undertaken less frequently, especially in young children. We evaluated PCR for th e detection of meningococcal DNA in 80 blood samples taken from patien ts with known or suspected meningococcal disease or from patients with other diagnoses (negative controls). Both the sensitivity and the spe cificity of the test were 100% for patients with confirmed cases of me ningococcal disease when the blood buffy coat was used (83 to 100% sen sitivity and 87 to 100% specificity with 95% confidence limits). Posit ive PCR results could be obtained from both blood buffy coat and serum samples. Sensitivity was unaffected by prior antibiotic treatment. PC R is a rapid, sensitive test that may be used to confirm a diagnosis o f meningococcal disease by using peripheral blood samples. Introductio n of this test into clinical laboratories may in some cases obviate th e need for lumbar puncture to be performed on patients with suspected meningococcal disease. Our results demonstrate that a substantial numb er of cases of meningococcal disease are not confirmed by conventional techniques and remain undiagnosed. If the PCR test described here was widely applied, the number of cases of meningococcal disease ascertai ned might rise by as much as 60% greater than that recognized at prese nt. It is likely that we are in a prevaccination era for meningococcal disease. Better case ascertainment is urgently required to assess the need for vaccines, to determine their costs and benefits, and to moni tor their efficacies.