Investigation of bacterial biofilm in the human middle ear using optical coherence tomography and acoustic measurements

• Optical coherence tomography is used to detect bacterial biofilms behind the eardrum.
• The wideband power reflectance is studied for ears with confirmed bacterial biofilms.
• Ears with biofilms have abnormal ‘reverse slopes’ of the power reflectance (0.5–2 kHz).
• Ears with biofilms have abnormally low normalized resistances between 1 and 3 kHz.

Children with chronic otitis media (OM) often have conductive hearing loss which results in communication difficulties and requires surgical treatment. Recent studies have provided clinical evidence that there is a one-to-one correspondence between chronic OM and the presence of a bacterial biofilm behind the tympanic membrane (TM). Here we investigate the acoustic effects of bacterial biofilms, confirmed using optical coherence tomography (OCT), in adult ears. Non-invasive OCT images are collected to visualize the cross-sectional structure of the middle ear, verifying the presence of a biofilm behind the TM. Wideband measurements of acoustic reflectance and impedance (0.2–6 [kHz]) are used to study the acoustic properties of ears with confirmed bacterial biofilms. Compared to known acoustic properties of normal middle ears, each of the ears with a bacterial biofilm has an elevated power reflectance in the 1 to 3 [kHz] range, corresponding to an abnormally small resistance (real part of the impedance). These results provide assistance for the clinical diagnosis of a bacterial biofilm, which could lead to improved treatment of chronic middle ear infection and further understanding of the impact of chronic OM on conductive hearing loss.This article is part of a Special Issue entitled “MEMRO 2012”.