Direct PCR assay for detection of Neisseria meningitidis in human cerebrospinal fluid

A PCR amplification was performed to detect Neisseria meningitidis insertio n sequence 1106 (IS-1106) in the human cerebrospinal fluid (CSF) in cases o f meningitis. The study included 27 CSF samples from suspected meningitis p atients. Although the inflammatory response in most of the samples was slig htly increased, the results showed that 7 (26 %) and 8 (30 %) CSF samples w ere diagnosed as meningococcal meningitis by Gram staining and by culture, respectively. The primers of the IS-1106 were used for direct diagnosis of N. meningitidis in the human spinal fluid after a minor treatment of the CS F samples. The sample was diagnosed as meningococcal meningitis, if a DNA b and of about 600 bp was detected in the ethidium bromide-stained agarose ge l. The 27 CSF samples were analyzed in a random manner. Of these, 18 sample s including the Gram staining- and culture-positive samples were also posit ive in PCR amplification. However, a CSF sample, which was diagnosed to be meningococcal meningitis in culture was negative in both Gram staining and PCR analysis. The specificity of the IS-1106 primers was determined to be 9 5 %, with 100 % sensitivity in comparison to Gram staining and culture. The primers were sensitive to 10 pg or more of meningococcal DNA. In addition, the PCR amplification showed high predictive values (89 and 100 %) in diag nosing meningitis in patients that were negative and positive responders wh en tested by culture and by Gram staining. In conclusion, the PCR amplifica tion of IS-1106 of N. meningitidis is specific and sensitive to both cultur e-positive and -negative meningococcal meningitis. Hence, PCR assay is high ly recommended for use in a rapid diagnosis of suspected meningitis patient s.