PCR assay for the diagnosis of pneumococcal meningitis

Abstract

Objective: Streptococcus pneumoniae is not an uncommon causative pathogen of acute bacterial meningitis, for which a slight delay in the management may result in death or serious sequelae. The traditional method of bacterial identification by culture requires at least 1-2 days, whereas use of PCR assay may allow much earlier recognition and confirmation of the bacteria. Materials and Methods: We designed a primer set targeting the amylomaltase gene (malM) of S. pneumoniae. Acute and convalescent cerebrospinal fluid (CSF) samples were collected from two patients of suspected acute bacterial meningitis. The acute CSF specimens were collected within the first hour the admission. The second specimens were collected during the convalescent stage after a 10-days treatment course with ceftriaxone. Polymerase chain reaction (PCR) assays were performed on the same day of sample collection. Results: The specificity and sensitivity of the PCR assay were demonstrated, and the latter shows that the latter could detect as few as 102 copies of molecules. In both patients the PCR assay identified the bacteria in the pre-treatment CSF samples, but not in the post-treatment specimens. All PCR assay results obtained in the first day were consistent with the culture results that were obtained on the fourth day of incubation. Conclusions: The use of PCR assays with the primer set targeting the malM gene would allow early recognition of the pneumococcal meningitis.