Laboratory Evaluation of Suspected Encephalitis
Laboratory Evaluation of Suspected Encephalitis
CSF PCR
STRATEGY
- urgent diagnosis needed to validate proper therapy
- isolation of HSV from culture is the reference method for diagnosis
- DNA PCR on CSF obtained by lumbar puncture is becoming the gold standard
- DFA performed on brain touch prep in the current case (LP contraindicated due to possible herniation risk
- comprehensive virus isolation from brain within days confirmed HSV-1
METHODS
- lyse virions and extract DNA
- PCR with two sets of primers
- pol gene of HSV, 179 bp amlpicon
- glycoprotein B gene of HSV, 148 bp amplicon
- does not amplify CMV, VZV, HHV 6
- cut pol amplicons with HhaI
- cleaves HSV-1 amplicon at a single site, two fragments
- cleaves HSV-2 amplicon at two sites, three fragments
- separate products on agarose gel with EtBr
NIAID Collaborative Antiviral Study Group. J Infect Dis 171:857, 1995
Tang Y-W et al. J Clin Microbiol 37:2127, 1999
Biopsy + | Biopsy - | ||
PCR + | 53 | 3 | |
PCR -
| 1 | 44 | |
- sensitivity 98%
- specificity 94%
- positive predictive value 95%
- negative predictive value 98%
NIAID Collaborative Antiviral Study Group. J Infect Dis 171:857, 1995
