Comparison of the Efficacy of Direct Immunofluorescence and Polymerase Chain Reaction for the Diagnosis of Herpes Simplex Virus and Varicella Zoster Virus Infections

Lee, Min Won; Sagong, Chan; Yu, Hee Joon; Kim, Joung Soo

Abstract

BACKGROUND
The optimal management of cutaneous herpes simplex virus (HSV) and varicella zoster virus (VZV) infections requires rapid and accurate diagnostic methods. Direct immunofluorescence (DIF) is known to be rapid and sensitive, but fresh samples are needed to ensure accuracy.
OBJECTIVE
We investigated the usefulness of DIF and polymerase chain reaction (PCR) in patients with HSV and VZV infections.
METHODS
From January 2012 to August 2013, a total of 134 patients (53 patients with HSV and 81 patients with VZV) were included in this study. Tissue smears were collected from the base of fresh vesicular lesions, and each IF slide was stained with an FITC-conjugated VZV-specific and HSV-specific monoclonal antibody. Viral DNA amplification by PCR was also examined. We compared the positivity rates of DIF and PCR according to virus type and skin lesion duration.
RESULTS
The overall positivity rate of PCR (94.0%) was higher than that of DIF (79.1%), and this difference was statistically significant (p<0.0001). DIF was positive in 67.9% and 86.4% of HSV and VZV cases, respectively, and this difference was statistically significant p<0.0001). The positivity rate of DIF decreased in skin lesions older than 7 days; however, PCR showed no significant differences in positivity rates according to skin lesion duration.
CONCLUSION
DIF is a rapid and discriminating test for early lesions of HSV and VZV. PCR is an especially sensitive test for old lesions, and aids in making a definitive diagnosis when combined with DIF.