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

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 rapidand 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 andVZV infections. Methods: From January 2012 to August 2013, a total of 134 patients (53 patients with HSV and 81 patients withVZV) were included in this study. Tissue smears were collected from the base of fresh vesicular lesions, and eachIF slide was stained with an FITC-conjugated VZV-specific and HSV-specific monoclonal antibody. Viral DNAamplification by PCR was also examined. We compared the positivity rates of DIF and PCR according to virus typeand skin lesion duration. Results: The overall positivity rate of PCR (94.0%) was higher than that of DIF (79.1%), and this difference wasstatistically significant (p???0.0001). DIF was positive in 67.9% and 86.4% of HSV and VZV cases, respectively, andthis difference was statistically significant (p???0.0001). The positivity rate of DIF decreased in skin lesions olderthan 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 especiallysensitive test for old lesions, and aids in making a definitive diagnosis when combined with DIF