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Background Bone and Joint Infections (BJI) have high morbidity and are difficult to treat infections. Culture-based diagnosis is limited in its ability to recover fastidious bacteria and because several organisms can be involved; culture times of up to two weeks may be necessary for certain bacteria. The sensitivity of culture is also negatively impacted by antibiotics received before surgery. Alternatively, molecular methods offer a promising improvement for the diagnosis of BJI. The goal of this study was to evaluate a development version of Biofire® Bone and Joint Infection (BJI) Panel (bioMerieux SA, BioFire Diagnostics, LLC) using synovial fluid samples. Methods 121 synovial fluid specimens were collected from patients with suspected bone and joint infection in a pilot evaluation. All specimens were collected and tested in culture by the sites using their standard of care practices; in parallel, a leftover volume of 200 µL was tested on the BJI panel. BJI panel results were then compared with culture and discordant results were investigated using a comparator assay (PCR/sequencing). Results 49 synovial fluid specimens (40%) were positive by culture vs. 72 with the BJI panel (59%). Of the 97 positive detections by the BJI panel, 58 were concordant with culture; the 39 additional organism detections were in majority confirmed by PCR/sequencing. Lastly, two false negative results corresponding to the same sample are under investigation. Conclusion The BJI Panel was able to identify most of the pathogens detected by culture. The majority of additional detections observed were confirmed by PCR/sequencing. While sites are currently enrolling more synovial fluids samples, these preliminary data suggest that a multiplexed molecular test may be more sensitive than culture to detect pathogens in synovial fluid specimens. The data presented in this abstract have not been reviewed by FDA or other regulatory agencies for In Vitro Diagnostic use. Disclosures B. Pons, bioMerieux: Employee, Salary. C. Jay, bioMerieux: Employee, Salary. T. Martin, bioMerieux: Employee, Salary. I. Sothier, bioMerieux: Employee, Salary. H. Savelli, bioMerieux: Employee, Salary. B. Kensinger, bioFire a bioMerieux company: Employee, Salary. F. Laurent, BioFire (bioMerieux company): Investigator, Research support. L. Abad, BioFire (bioMerieux company): Investigator, Research support. C. Murphy, BioFire (bioMerieux company): Investigator, Research support. A. Craney, BioFire (bioMerieux company): Investigator, Research support. B. Schmitt, BioFire (bioMerieux company): Investigator, Research support. A. Waggoner, BioFire (bioMerieux company): Investigator, Research support. S. Butler-Wu, BioFire (bioMerieux): Investigator, Research support. C. Costales, BioFire (bioMerieux company): Investigator, Research support. J. Bien-Bard, BioFire (bioMerieux): Investigator, Research support. J. Mestas, BioFire (bioMerieux): Investigator, Research support. J. Esteban, BioFire (bioMerieux): Investigator, Research support. L. Salar-Vidal, BioFire (BioMerieux company)): Investigator, Research support. A. Harrington, BioFire (bioMerieux company): Investigator, Research support. S. Collier, BioFire (BioMerieux Company): Investigator, Research support. A. Leber, BioFire (bioMerieux company): Investigator, Research support. K. Everhart, BioFire (bioMerieux company): Investigator, Research support. J. M. Balada-Llasat, BioFire (bioMerieux company): Investigator, Research support. J. Horn, BioFire (bioMerieux company): Investigator, Research support. S. Magro, bioMerieux: Employee, Salary. K. Bourzac, BioFire a bioMerieux company: Employee, Salary.

Background In 2016, our academic medical center implemented the BioFire® FilmArray® Meningitis/Encephalitis Panel (MEP), which detects 14 viral, bacterial, and fungal pathogens. Institutional guidelines recommended the test be used in nonimmunocompromised patients age ≥2 years only if the cerebrospinal fluid (CSF) white blood cell (WBC) count was >10 cells/mm3. Methods We reviewed all MEP performed at our institution over 2 years (January 1, 2017 to December 31, 2018). We collected CSF WBC count, protein, and glucose; MEP results; CSF culture results; and demographics. We excluded children age Results Of 453 patients, 311 met inclusion criteria. The median age was 51, 51% male. Median CSF indices: WBC/mm3 = 4, protein = 57 mg/dL, glucose = 66 mg/dL. MEP positivity rate = 12% (37/311): viruses (29/37), bacteria (7/37), and fungi (1/37). Positive bacterial/fungal MEP results compared with CSF culture are summarized in Table 1. No clinically significant discordant negative MEP results occurred compared with CSF culture, cryptococcal antigen, or other viral PCR testing. Of the 311 patients, 184 (59%) had ≤10 CSF WBC/mm3. Of these, 4 had positive MEP results: 1 enterovirus, 1 human herpes virus 6 (HHV-6) and 2 varicella zoster virus (VZV). The HHV-6 was judged clinically insignificant. The 2 VZV cases had concomitant shingles and were already on acyclovir. No clinically significant MEP results occurred in 110/311 (35%) patients with ≤ 2 CSF WBC/mm3. Conclusion In nonimmunocompromised patients, age ≥ 2, with ≤ 10 CSF WBC/mm3 on lumbar puncture, positive MEP results were rare and the clinical significance of the 4 positives was debatable. A hard-stop restriction in this setting could have reduced overall use by up to 59% and resulted in significant cost savings. Lower CSF WBC/mm3 cut-offs could be considered and still improve MEP utilization. Disclosures All Authors: No reported Disclosures.