Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1378 page)

   General recommendations for viral culture apply.

   Specimens should be collected early in acute infection.

   Specimens should be collected according to general recommendations for virus culture of the specimen type. Specimens from cutaneous or mucous membranes are most commonly submitted for viral culture to rule out HSV. Samples should be taken from fresh, wet lesions, ideally from intact vesicles after unroofing.

   Most specimens should be placed in a viral transport medium and transported at 4°C.

   Interpretation

   
Expected results:

   
Positive:
Cell cultures positive for HSV indicate probable active infection. Occasionally, positive cultures represent asymptomatic shedding of virus that may be clinically insignificant.

   
Negative:
Negative cell cultures do not rule out HSV infection, especially for CSF and other nonvesicular lesions.

   Limitations

   There may be poor sensitivity for certain specimen types, such as CSF. Molecular diagnostic testing may improve detection from these specimens.

   
Common pitfalls:
Collection of specimens from dried, crusted lesions.

   HSV-specific DFA, performed on cells from the base of vesicles or wet ulcers, provides rapid and specific identification of HSV infection.

   PCR is the most sensitive method for HSV detection and is most useful for diagnosis of CNS infections.