Clinical utility of a polymerase chain reaction assay in culture-negative necrotizing otitis externa

Objective: This study describes a subset of necrotizing otitis externa (NOE) patients with a refractory disease and negative cultures. In these cases, we decided to use a polymerase chain reaction (PCR) assay from surgically obtained tissue under sterile conditions to improve pathogen detection sensitivity. Study Design: Retrospective case review. Setting: Academic medical center. Patients: Nineteen consecutive patients diagnosed with NOE between January 2008 and January 2014 inclusive. Three patients of this cohort presented a culture-negative disease. Interventions: Diagnostic. Main Outcome Measures: Positive detection of pathogens using a PCR assay in cases with a complicated course of NOE and clinical resolution of the disease after targeted therapy according to PCR results. Results: Surgical samples were obtained under sterile conditions from three patients with negative cultures and a refractory disease course of NOE. PCR assays were performed using pan-bacteria and pan-fungi protocols. In all three samples, a positive result for a fungal pathogen was recorded and followed by successful empirical targeted therapy. Conclusion: Patients who present with a refractory culture-negative NOE should be suspected as suffering from a fungal disease. The PCR assay may be an important laboratory adjunct in detecting pathogens responsible for NOE and can aid to promote therapy and disease resolution.