RESUMO
A polymerase chain reaction (PCR) protocol for the rapid detection of meningococcal DNA in cerebrospinal fluid (CSF) was developed and optimized. A set of primers based on Neisseria surface protein A (nspA) gene sequence was designed to amplify a 481-bp product specific for N. meningitidis. We tested 85 N. meningitidis strains obtained from patients with meningococcal meningitis and 112 CSF samples from patients with suspected meningococcal meningitis. No amplification of the nspA gene was observed from other Neisseriaceae species (except from N. gonorrhoeae) and from other bacteria frequently associated with meningitis. N. meningitidis belonging to different serogroups yielded the same product after PCR amplification. The sensitivity and specificity of our protocol was determined by comparing the results of specific amplification of nspA gene by PCR reaction (nspA-PCR) with those obtained by conventional methods. All positive samples by conventional methods were confirmed by nspA-PCR, whereas 48% of negative samples after culture and latex agglutination tested positive by nspA-PCR. The use of nspA-PCR proved to be a rapid diagnostic method, in which sensitivity and specificity may not be affected by prior antibiotic treatment.
