[Diagnosis of meningococcal disease by polymerase chain reaction]

The objective of the present study was to evaluate the application of a rapid and simple PCR technique to diagnose meningococcal disease.

A retrospective study was undertaken from January 1999 to June 2002, comprising 110 samples of cerebrospinal fluid (CSF) or plasma from 110 different pediatric patients attending the Hospital Sant Joan de Déu of Barcelona. The selection of patients was based on their diagnosis at discharge: Forty three patients had a discharge diagnose of meningococcal disease (13 meningitis, 12 sepsis and 18 sepsis with meningitis) while 67 had clinical conditions other than meningococcal disease. The samples were processed following standard bacteriological methods (Gram smear and culture) and a PCR technique designed to amplify a segment of the meningococcal insertion sequence IS1106 was performed.

Sensitivity of PCR in the group of patients with a clinical diagnosis of meningococcal disease was 93% while sensitivity of the culture was 55.8%. Samples from 19 patients were processed once treatment with -lactam antibiotics had begun (range 8-144 hours), and positive PCR results were seen in 17 cases (sensitivity: 89.4%); a positive culture was observed in two cases of pre-treated patients (sensitivity 10.5%). A false positive result was detected in the group of patients with non-meningococcal disease (specificity 98.5%).

The application of this PCR permits a rapid (roughly 5 hours), specific and sensitive method that increases the microbiologic confirmation of meningococcal disease, mainly in patients who have received previous antibiotic treatment.