Five of the 34 patients, whose samples were negative at the time of diagnosis were later found to have EBV, VZV, SP, HEV, and HSV-1 infection when investigated by conventional studies. These discrepancies were perhaps attributable to inter-specimen differences at varying stages of infection. Of the other 29 patients who tested negative for all pathogens, 10 had indeterminate CSF parameters, whereas 19 showed findings consistent with bacterial or viral infection. The presence of clinical features of meningitis and indeterminate CSF findings in the 10 patients may be attributed to conditions other than acute viral or bacterial meningitis. In contrast, meningitis in the 19 patients with CSF findings consistent with bacterial or viral infections may have been caused by pathogens other than the 12 assayed by the Seeplex Meningitis ACE Detection kit. Alternatively, the concentration of pathogens in the CSF may have been too low to permit detection.