1640. Acyclovir use in infants and children (0-18 years) in Pediatric hospitals in Australia and New Zealand for suspected herpes simplex virus infection

BACKGROUND: Non-specific presentations of severe herpes simplex virus (HSV) infections and high risk of adverse outcomes have driven empiric acyclovir use. We therefore audited acyclovir prescribing in Australia and New Zealand for suspected HSV infection. METHODS: All children (0-18 years) prescribed intravenous (IV) acyclovir for suspected HSV infection in eight paediatric hospitals in Australia and New Zealand between 1 January 2019 and 31 December 2019 were included. Clinical data were extracted from patient records. RESULTS: IV acyclovir was prescribed for 1426 suspected cases, of whom 114 (8%) subsequently had proven HSV infection; 0.8% severe (9 encephalitis, 3 disseminated) and 7.2% (102) non-severe. Median age of the 1426 suspected cases was 4-months (IQR 0-49, range 0-223); 30% being neonates (<28 days), 17% aged 29 days-to-3 months and 53% aged >3-months. Suspected encephalitis (55%) and disseminated disease (29%) were the most common indications for prescribing acyclovir. 88% lacked risk factors and 90% had no potential identifiable source. 57% had CSF obtained, 25% and 13% had >1 surface swab and blood sent for HSV PCR testing respectively, whilst 20% had no HSV investigations. 34% were admitted to an intensive care unit. Median IV acyclovir duration was 1-day (IQR 1-2; range 0-81); 0.5% experienced nephrotoxicity and 2% had an extravasation injury. The median length-of-hospital stay was 4-days (IQR 2-9, range 0-307), 92% were well at discharge. Non-HSV infections (47%) and seizure disorders (15%) were the most common discharge diagnoses. CONCLUSION: This study suggests frequent unnecessary empiric acyclovir use, with 8% of children having proven HSV infection; minority severe (0.8%) and 20% of children not having any HSV investigations. National algorithms identifying high-risk age groups and clinical features of neonatal HSV infection and HSV encephalitis are needed to better guide acyclovir use and limit unnecessary treatment. DISCLOSURES: All Authors: No reported disclosures