PCR products were cloned into the vector pUC19 (size, 2,686 bp). The cloned plasmids were harvested, DNA concentrations were measured, and the numbers of target copies were calculated (1 µg of a 1,000-bp DNA unit equals 9.1 × 10 11 copies). The sensitivity of the system was evaluated by amplifying 10-fold serial dilutions of each plasmid (concentrations, 10 4 to 10 -1 copies/20 μL), with distilled water as the negative control. Samples were PCR-amplified and electrophoresed in 2% (w/v) agarose gels. Analytical sensitivity was defined as the lowest template copy number for which amplified products were consistently [11, 12] . Bacterial meningitis was differentiated from viral or aseptic meningitis by a WBC count of more than 100 cells/mm 3 with neutrophil dominance and a ratio of CSF glucose/serum glucose level of less than 0.4. Cases with insignificant WBC count or discrepant results in different parameters were classified into the undetermined group. The median patient age was 27 yr (range, 1 month to 72 yr). For the verification study, we tested only the 78 samples collected at the time of diagnosis, i.e., before antibiotic therapy was initiated. Another set of 118 samples was used to assess discrepancies in positive results obtained from the same patients. Samples that were blood-colored, showed leakage, were aged over 12 hr, and strongly suspected of being contaminated (with discrepancies in the pathogens detected in consecutive tests), were excluded. All samples were assessed by conventional CSF microscopic analysis, staining, and culture. Control CSF samples were collected from 27 patients; of these 