2464. Partnerships in the Field: Using Real-time Sequencing to Enhance Epidemiologic Investigation and Response to a Norovirus Outbreak

BACKGROUND: Norovirus is a common cause of infectious gastroenteritis and frequently leads to hospital-based outbreaks of gastrointestinal (GI) illness. We utilized hospital-wide surveillance to detect outbreaks of GI illness among patients and healthcare workers (HCW). Real-time norovirus sequencing was applied to establish conclusive links between patient cases. METHODS: Patient cases of healthcare-associated GI illness were detected through house-wide microbiologic surveillance. HCW cases were defined as acute episodes of vomiting and/or diarrhea that began within 48 hours of the last shift. Outbreak procedures were implemented on a unit when 3 or more cases were identified within 48 hours. Traditional epidemiologic methods were used, including an epidemic curve and line listing, while instituting local control measures. De-identified clinical stool samples positive for norovirus from any hospital unit during the defined outbreak time period were analyzed. Sanger sequencing was performed using primer sets targeting the norovirus VP1 capsid and polymerase regions. Capillary electrophoresis was implemented on a 3500 Genetic Analyzer (Applied Biosystems) and analysis was performed via MEGA7. RESULTS: Epidemiologic surveillance identified a norovirus outbreak involving 11 patients on a single unit. Sequencing was performed on 20 norovirus positive stool samples, of which 13 shared 100% identity across both the VP1 and polymerase regions. Of these 13, 10 specimens were from patients epidemiologically linked to the outbreak; 3 specimens were from patients located on 2 geographically separate floors, not epidemiologically linked to the outbreak. Identification of cases outside of the outbreak unit prompted additional hospital-wide infection prevention interventions, including increased education and messaging, changes in hand hygiene practice, and prohibition of shared food for staff. CONCLUSION: Real-time sequencing confirmed epidemiologically linked cases of norovirus during an outbreak and identified additional transmission events not detected by conventional epidemiologic methods. Partnership between hospital epidemiology and the laboratory identified the need for hospital-wide infection prevention measures to halt ongoing transmission. DISCLOSURES: All authors: No reported disclosures.