1776. Step-Wise Algorithm for the Detection of Respiratory Viruses: Integrating a Rapid Influenza A/B and RSV PCR with a Multiplex Respiratory Virus Panel to Target High-Risk Patient Populations

BACKGROUND: In clinical settings, multiplex molecular panels are becoming increasingly common for the detection of respiratory pathogens. Little evidence is available to guide appropriate use of respiratory multiplex panels, particularly with respect to the patient populations most likely to benefit from such testing. METHODS: During the 2018–2019 influenza season, all patients with a nasopharyngeal swab submitted for respiratory virus detection were initially tested on a commercial rapid PCR platform for influenza A/B and respiratory syncytial virus (RSV) (Cepheid GeneXpert, Sunnyvale, CA). Patients with negative swabs were reviewed by a laboratory physician based on pre-defined criteria (Table 1) for additional testing by a laboratory-developed multiplex assay for parainfluenza 1/2/3, adenovirus, and human metapneumovirus (hMPV). RESULTS: In total, 1144 nasopharyngeal swabs were tested. 287 (25.1%) were positive on the GeneXpert: influenza A (234, 81.5%), influenza B (13, 4.5%), and RSV (40, 13.9%). Of the patients who tested negative, 234 (27.3%) met criteria for further respiratory virus testing. The most commonly detected viral pathogens on the multiplex assay were hMPV (20/30, 66.7%), parainfluenza 3 (7/30, 23.3%) and adenovirus (3/30, 10%). The yield of the multiplex assay was highest for patients selected for antimicrobial stewardship (AS) criteria (13/56, 23.2%), followed by transplant (2/16, 12.5%), HIV (7/64, 10.9%), cystic fibrosis (2/19, 10.5%), critical care (6/68, 8.8%), and other/upon physician request (0/11, 0%). Of the patients who received multiplex testing for AS criteria and tested positive for a viral pathogen, only 3/13 (23.1%) had antibiotics discontinued by the medical team within 48 hours of the report. CONCLUSION: Additional testing for respiratory viral pathogens had low overall diagnostic yield, and further refinement of the algorithm is needed to better target utilization of respiratory virus testing. The patient population with the highest yield (those who met AS criteria) failed to demonstrate consistent timely discontinuation of unnecessary antibiotics by the medical team. Implementation of respiratory multiplex panels would be strengthened by collaboration with AS teams. [Image: see text] DISCLOSURES: All authors: No reported disclosures.