Diagnosis of meningococcal meningitis by broad-range bacterial PCR with cerebrospinal fluid

Abstract

We used broad-range bacterial PCR combined with DNA sequencing to examine prospectively cerebrospinal fluid (CSF) samples from patients with suspected meningitis. Fifty-six CSF samples from 46 patients were studied during the year 1995. Genes coding for bacterial 16S and/or 23S rRNA genes could be amplified from the CSF samples from five patients with a clinical picture consistent with acute bacterial meningitis. For these patients, the sequenced PCR product shared 98.3 to 100% homology with the Neisseria meningitidis sequence. For one patient, the diagnosis was initially made by PCR alone. Of the remaining 51 CSF samples, for 50 (98.0%) samples the negative PCR findings were in accordance with the negative findings by bacterial culture and Gram staining, as well as with the eventual clinical diagnosis for the patient. However, the PCR test failed to detect the bacterial rRNA gene in one CSF sample, the culture of which yielded Listeria monocytogenes. These results invite new research efforts to be focused on the application of PCR with broad-range bacterial primers to improve the etiologic diagnosis of bacterial meningitis. In a clinical setting, Gram staining and bacterial culture still remain the cornerstones of diagnosis.

FIG. 1

Sensitivity of the bacterial PCR. A dilution series of N. meningitidis DNA was analyzed by bacterial PCR and gel electrophoresis. The arrow indicates the band of the expected size. N. meningitidis DNA was used in the PCR in amounts of 500 ng (lane 1), 50 ng (lane 2), 5 ng (lane 3), 500 pg (lane 4), 50 pg (lane 5), 5 pg (lane 6), 500 fg (lane 7), 50 fg (lane 8), 5 fg (lane 9). Lane +, positive control; lane −, negative control; lane L, 1-kb DNA ladder (Gibco BRL, Gaithersburg, Md.).