RESUMO
BACKGROUND: The aim of this work was to evaluate the applicability of polymerase chain reaction (PCR) in the microbiological diagnostic of meningococcal meningitis as compared with the conventional methods (Gram stain and culture). METHODS: One hundred and fifteen cerebrospinalis fluid samples from 115 patients with suspicious symptoms of meningitis were studied. 47 of them belonged to patients suspicious for meningococcal disease; 28 to patients with bacterial meningitis of other infectious etiologies; 10 to patients with meningitis showing lymphocytic pleocytosis and 30 to patients with an unconfirmed meningitis. The cerebrospinalis fluid samples were processed for culture by standard procedures and by PCR according to the method described by Newcombe et al for peripheral blood samples. RESULTS: Thirty five out of 39 patients suspicious of meningococcal meningitis were microbiologically confirmed, being 22 culture and PCR positive, 3 microscopically and PCR positive, 1 only microscopically positive, and 9 positive only by PCR. By using PCR methodology, the number of confirmed diagnostics of meningococcal meningitis increased in a 23% as compared to those obtained by microscopic observation and culture. Sensitivity, specificity, predictive positive value and predictive negative value were 87.1, 98.7, 97.1 and 94.1 respectively for the PCR method. CONCLUSIONS: Our results indicate that PCR can be used on routine basis as a complementary technique to the standard laboratory procedures for diagnosis of meningococcal meningitis.