1783. More than Which Molecular Test: Following the Directions in How and Who to Test in the Diagnosis of Influenza

BACKGROUND: The CDC and IDSA recommend testing hospitalized patients with suspected influenza using molecular assays, in part to implement precautions to prevent transmission. Both PCR and a rapid isothermal nucleic acid amplification test (NAAT) for influenza detection are available at the University of Utah Health (UU). The UU has required the more-sensitive PCR to discontinue isolation for suspect in patients, but we hypothesized the NAAT could be sufficient in most patients. METHODS: A retrospective review of influenza diagnostics pre- and post-reinforcement of proper test procedures was performed across a university healthcare system, including a 650-bed tertiary care and 100-bed cancer hospital. During August 2018, providers and staff involved in testing were interviewed to describe their practices. Gaps were addressed in September 2018 with flyers outlining procedures, providing optimal sampling supplies, and EHR prompts for appropriate specimen type. A subset of UU patients tested by both NAAT and PCR within a 48 hour period were identified from the corporate data warehouse as Pre (September 2016 through March 2018) or Post reinforcement (October 2018 through March 2019). Agreement within PCR/NAAT test pairs was determined, with chart reviews of patients with discrepant results. Time of testing from the onset of symptoms was noted, and flu-like symptoms were defined as fever (>38°C) and cough or sore throat. RESULTS: Prior to reinforcement, most hospital staff were unaware of the optimal specimen type and collection swab for NAAT vs. PCR. Units initially lacked appropriate sampling supplies for NAAT. Providers complained of needing to confirm negative NAAT for inpatients with questionable symptoms, and supported the reinforcement to target follow-up PCR in those clearly symptomatic or immunocompromised. Concordance with NAAT and PCR pre- and post-reinforcement of proper test procedures when both methods were done is shown in the Figure. CONCLUSION: Diagnosis of influenza is important in hospitalized patients. In addition to selecting a sensitive assay, attention to optimize test performance is critical. Our results suggest there is a need to train and monitor clinicians in identifying who to test and when, what specimen to collect and how, and in interpreting results. [Image: see text] DISCLOSURES: Kimberly Hanson, MD, MHS, BioFire: Consultant, Grant/Research Support; T2 Biosystems: Consultant.