Implementation of In-house PCR Testing for Herpes Simplex Virus Encephalitis: Impact on Patient Acyclovir Exposure

BACKGROUND: HSV encephalitis is a life-threatening disease process that requires prompt treatment. Diagnosis is often dependent upon nucleic acid studies of CNS samples. We introduced the Film Array Meningitis/Encephalitis (ME) Panel, a qualitative multiplexed nucleic acid-based diagnostic test for a variety of CNS pathogens, including HSV, in June 2016. It replaced an equivalent reference laboratory nucleic acid amplification test. The intent was to provide a more timely result and decrease unnecessary drug exposure to the patient. METHODS: We conducted a retrospective chart review of adult patients (>18 yo) admitted between June-September 2015 and June-September 2016 who underwent CSF testing for HSV and received empiric acyclovir. The aim was to determine whether the newly available test resulted in fewer doses of acyclovir in those who tested negative for a herpes virus as compared with those tested with the previously available assay. We excluded those found to be positive for HSV-1, HSV-2, or VZV in the CSF. We defined a dose as any administration of acyclovir or valacyclovir to the patient. RESULTS: Results of the diagnostic assay returned significantly faster after institution of the ME panel (4.9 days (118 hours) vs .09 days (2.25 hours)). Due to the non-normal distribution of acyclovir dosing, comparisons were made with the Wilcoxson Rank-sum. The institution of the ME panel for all CSF studies significantly impacted our use of acyclovir, as patients with negative tests for HSV PCR in the CSF received fewer doses of acyclovir after implementation of the ME panel (median (25(th)–75(th) percentiles) 6 (2–13.5) vs 3 (1–6), P = .018). CONCLUSION: Implementation of a rapid diagnostic PCR based test for HSV 1 and HSV 2 in 2016 significantly reduced the number of empiric acyclovir doses administered during the summer of 2016 compared with the summer of 2015 in patients testing negative for the condition. DISCLOSURES: All authors: No reported disclosures.