646. Evaluation of the Utility of a New Comprehensive Molecular Assay to Test for the Common Pathogens that Cause Lower Respiratory Tract Infections and its Potential Impact on Antibiotic Therapy

Abstract

Abstract Background Lower respiratory tract infection (LRTI) has high mortality among critically ill patients. The current standard of care for diagnosing bacterial causes of LRTI is respiratory culture, which is time consuming and insensitive. The FilmArray Pneumonia Panel (FA-Pneumo) (Biofire Diagnostics, Salt Lake City, UT) is FDA-cleared for the detection of lower respiratory tract pathogens (bacteria, atypical bacteria, and viruses) directly from lower respiratory tract specimens. Here, we evaluated the performance of the FA-Pneumo assay in bronchoalveolar lavage (BAL) samples and assessed its potential impact on antibiotic therapy. Methods A total of 61 BAL samples collected for respiratory culture from intensive care unit patients aged 18 years and older who had symptoms consistent with LRTI were included in the study. Remnant BAL samples were tested using the FA-Pneumo and results were compared with standard of care respiratory culture results. We then conducted a chart review to determine the potential impact of FA-Pneumo results on antibiotic therapy. Results The results of 48 out of 61 BAL samples (78.7%) were the same when comparing FA-Pneumo with a standard of care respiratory culture. Two patients grew Stenotrophomonas maltophilia and 1 patient grew Achromobacter. Importantly, neither of these organisms is targeted by the FA-Pneumo assay. Three patients (4.9%) had viral LRTI, with 9 patients (14.8%) having bacterial/viral co-infection. A total of six patients with methicillin-susceptible Staphylococcus aureus (MSSA) remained on vancomycin therapy for a median of 1.5 days (range 0–7 days) and all three patients with viral LRTI remained on broad-spectrum antibiotic therapy for a median of 4 days (range 3–13 days). All three patients with ESBL-positive Enterobacteriaceae detected by FA-Pneumo and culture were not started on appropriate antibiotic therapy until >48 hours after the FA-Pneumo would have been resulted. Conclusion The FA-Pneumo assay has the potential to lead to earlier discontinuation of vancomycin for patients with MSSA LRTI and earlier broadening of therapy for ESBL LRTI. Providers should be aware of the inability of the FA-Pneumo to detect S. maltophilia and Achromobacter species. Disclosures All authors: No reported disclosures.