The Deceptive Reassurance of a “Negative” Test – A Difficult Case Highlighting the BioFire^© Meningitis/Encephalitis Panel and Medical Heuristics

<b>Purpose:</b> Neurolisteriosis is a difficult neurologic infectious disease to diagnose. Here, we present a case in which the diagnosis was suspected, but repeated testing for the pathogen was negative. Ultimately the diagnosis was made after the patient iatrogenically worsened. <b>Results:</b> This prompted an investigation into the widely used diagnostic test, the BioFire© Meningitis/Encephalitis Panel. Although the company reports high sensitivities and specificities for the panel, real world studies have demonstrated insufficient evidence that all 14 pathogens tested on the panel have similar results. <b>Conclusion:</b> This case is a reminder of the heuristics involved in medicine and how with every medical advancement, clinicians should always go back to the fundamentals of history-taking and physical examinations to ensure no steps have been overlooked in the diagnosis and management of challenging cases.