Project Description

Investigating Mechanisms of Sensory Hearing Loss in Chronic Suppurative Otitis Media

Anping Xia
Anping XiaPhD
Peter Santa Maria
Peter Santa Maria MBBS, PhD
graphical abstract for the project showing selection for the gene via PCR

Hearing cells are stained red (Myo7) to show sensory cell loss in the ipsilateral ear.

We aim to investigate how sensorineural hearing loss is caused by chronic suppurative otitis media (CSOM) or severe chronic middle ear infections. CSOM, a neglected tropical disease that afflicts 330 million people worldwide, is the most common cause of permanent hearing loss among children in the developing world. It is characterized by a chronically discharging infected middle ear, and there is currently no effective medical therapy or cure. The bacterium, Pseudomonas aeruginosa (PA), is the leading culprit. PA colonizes the middle ear via a hole in the tympanic membrane and establishes itself into a biofilm community, complicating attempts to treat and fully eradicate infection. Over the course of the disease, the infection waxes and wanes as the population of bacteria within the biofilm responds, in part, to immune attack or topical antibiotics. This waxing and waning of bacterial infection leads to permanent sensory hearing loss via an unknown mechanism.

Our lab has recently created and validated a novel PA CSOM animal model that mimics the human condition. Specifically, we create the infection by inoculating PA in the right state (phenotype) and dose, which results in an infection that persists beyond six months, waxes and wanes upon topical fluoroquinolone therapy, and leads to hair cell death, over time, like in the human disease. Previous investigations by others relied on acute infection models based on non-PA bacteria. In contrast, our unique model of PA CSOM now allows us to observe development of the infection in the inner ear and identify agents and/or processes that may be causing the resulting sensory hearing loss. Our studies would help determine whether permanent hearing loss is preventable in CSOM and, if so, guide strategies for therapeutic intervention.