Enteroviruses and HSV-2 are the leading causes of adult aseptic meningitis, and PCR is of diagnostic value. However, in most cases of encephalitis, the etiology remains undefined.

PCR of fecal specimens obtained throughout the course of enteroviral meningitis had the highest clinical sensitivity for detecting enterovirus. It is recommended that, in addition to performance of CSF PCR, fecal samples collected from patients with suspected enteroviral meningitis should be tested by PCR, especially when the duration of symptoms is >2 days.

Objective: To evaluate the usefulness of the broad range bacterial rDNA polymerase chain reaction (PCR) method combined with DNA sequencing in the aetiological diagnosis of intracranial or spinal infections in neurosurgical patients. Methods: In addition to conventional methods, the broad range bacterial PCR approach was applied to examine pus or tissue specimens from cerebral or spinal lesions in patients treated in a neurosurgical unit for a clinical or neuroradiological suspicion of bacterial brain abscess or spondylitis. Results: Among the 44 patients with intracranial or spinal lesions, the final diagnosis suggested bacterial disease in 25 patients, among whom the aetiological agent was identified in 17. A causative bacterial species was identified only by the rDNA PCR method in six cases, by both the PCR methodology and bacterial culture in six cases, and by bacterial culture alone in five. All samples in which a bacterial aetiology was identified only by the PCR approach were taken during antimicrobial treatment, and in three patients the method yielded the diagnosis even after > 12 days of parenteral treatment. One case also identified by the PCR approach alone involved a brain abscess caused by Mycoplasma hominis, which is not readily cultured by routine methods. Conclusions: In patients with brain abscesses and spinal infections, the broad range bacterial rDNA PCR approach may be the only method to provide an aetiological diagnosis when the patient is receiving antimicrobial treatment, or when the causative agent is fastidious.

We could not find evidence of VZV, CMV, or HHV-6 in the pathogenesis of RALM, although most patients were previously infected by those viruses. Herpes simplex virus 2 was detected from the CSF in most patients, and often repeatedly, which further confirms the role of this virus in RALM. The causative diagnosis was obtained only by PCR, whereas antibody analysis was not clinically useful.