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

Abstract

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. Retrospective case review. Academic medical center. Nineteen consecutive patients diagnosed with NOE between January 2008 and January 2014 inclusive. Three patients of this cohort presented a culture-negative disease. Diagnostic. 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. 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. 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.