CONFIRMATION OF SUSPICIOUS CASES OF MENINGOCOCCAL MENINGITIS BY PCR AND ENZYME-LINKED-IMMUNOSORBENT-ASSAY

A significant problem in efficacy trials of meningococcal vaccines has been accurate identification of all cases of meningococcal disease th at occur in study populations. The accuracy of case determination woul d be improved by utilizing methods which confirm or disprove suspiciou s cases of meningococcal disease that are culture negative, A collecti on of serum and cerebrospinal fluid (CSF) samples from a meningococcal vaccine field trial performed in Iquique, Chile, were utilized to ass ess the status of patients for whom cultures, Gram stains, and clinica l evaluations for meningococcal disease were available. Nested PCRs (n PCRs) for amplification of Neisseria meningitidis DNA in CSF samples a nd enzyme-linked immunosorbent assays (ELISAs) for quantification of s erum immunoglobulin G antibodies specific for N. meningitidis were use d in combination to confirm or eliminate cases classified by physician s as suspicious for meningococcal disease, Samples from 12 of 79 patie nts suspected of having meningococcal meningitis tested positive by bo th methods; specimens from 61 of the 79 were negative by both methods; and samples from 6 patients yielded ambiguous results, and these case s remained unconfirmed, Direct sequence analysis Of amplified DNA from patients suspected of having meningococcal disease confirmed that 2 o f the 12 newly confirmed cases were not attributable to the typical ep idemic strain (B:15:P1,[7],3) while the others were due to the epidemi c strain, A combination of nPCR and ELISA reduced the number of suspic ious cases in this study from 79 to 6, thereby improving the potential for assessment of vaccine efficacy. Molecular identification by nPCR in conjunction with immunological assessment of patient response could be considered diagnostic of disease in future testing of meningococca l vaccines to improve efficacy analyses.