OCT used to spot middle-ear-infection biofilms behind the eardrum

Champaign, IL--Otitis media (OM), a middle-ear infection that is generally recognized as a biofilm-related disease, is now being visualized by researchers at the University of Illinois who use optical coherence tomography (OCT) as a monitoring tool.¹

“We know that antibiotics don’t always work well if you have a biofilm, because the bacteria protect themselves and become resistant,” says University of Illinois electrical and computer engineering professor Stephen Boppart. “In the presence of a chronic ear infection that has a biofilm, the bacteria may not respond to the usual antibiotics, and you need to stop them. But without being able to detect the biofilm, we have no idea whether or not it’s responding to treatment.”

“We send the light into the ear canal, and it scatters and reflects from the tympanic membrane and the biofilm behind it,” says graduate student Cac Nguyen, the lead author of the paper. “We measure the reflection, and with the reference light we can get the structure in depth.” The single scan is performed in a fraction of a second and images a few millimeters deep behind the eardrum. Thus, doctors can see not only the presence of a biofilm, but also how thick it is and its position against the eardrum.

This marks the first demonstration of using an ear OCT device to detect biofilms in human patients. To test their device, the researchers worked with clinicians at Carle Foundation Hospital in Urbana, Ill., to scan patients with diagnosed chronic ear infections, as well as patients with normal ears. The device identified biofilms in all patients with chronic infections, while none of the normal ears showed evidence of biofilms.

The researchers next plan to investigate different ear pathologies, particularly comparing acute and chronic infections, and will examine the relationship between biofilms and hearing loss. They hope that improved diagnostics will lead to better treatment and referral practices.

The researchers hope to make their device (currently a hand-held prototype) even more compact, easy to use, and low-cost. The device company Welch Allyn (Skaneateles Falls, NY) is a collaborator on the project, which was funded by the National Institutes of Health. Boppart’s group and its collaborators also will work to apply OCT imaging to other areas commonly examined by primary-care physicians. The ear-imaging device is the first in a suite of OCT-based imaging tools that the group plans to develop. Doctors could change the tip of the new OCT device, for example, to look at the eyes, mouth, nose, or skin.

REFERENCE:

1. Cac T. Nguyen et al., PNAS, published May 28, 2012.