Detection of Microbiota in Post Radiation Sinusitis

Abstract

Objectives: A shift in the microbiota of chronic rhinosinusitis has been described after radiotherapy to the sinonasal cavity and skull base. There is a paucity of literature characterizing the bacteriology of post radiation sinusitis using next-generation gene sequencing techniques. This study aims to describe and compare the microbial flora of rhinosinusitis after radiotherapy using both culture and molecular techniques for microbial DNA detection. Methods: The medical records of patients treated with external beam radiation for sinonasal, nasopharyngeal, or skull base malignancy were reviewed at a tertiary care facility. Patients’ sinonasal cavities were swabbed for routine culture or brushed for molecular gene sequencing. Swab specimens were processed for standard microbial culture, and brush specimens were sent for gene sequencing at Micro GenX Laboratory (Lubbock, Texas, USA). Results: Twenty-two patients were diagnosed with chronic sinusitis after undergoing radiotherapy. Staphylococcus aureus was the most common organism identified by both culture and gene sequencing, followed by Pseudomonas aeruginosa. Several additional organisms were detected by gene sequencing that were not isolated by routine culture techniques. Gene sequencing identified pathogens differing from culture results in 50% of patients examined. Conclusion: The bacteriology of post radiation sinusitis appears to resemble the microorganisms responsible for chronic sinusitis in healthy adults. Next generation gene sequencing techniques may reveal additional organisms responsible for sinusitis and provide complementary results that may impact the medical treatment of post radiation sinusitis.