Clinical researchers at The University of Nottingham have been studying how to improve the treatment of glue ear, a condition common in children during which mucus amasses behind the ear drum and impairs hearing. Typically, grommets are inserted for ventilation, but a considerable number of patients return with infections.
To directly combat this, the researchers developed biodegradable pellets that can be implanted during grommet surgery to deliver antibiotics right to where the infections happen.
Following research by this group and others, it is now recognised that glue ear is caused by biofilms — bacteria which grow together in a protective ‘slime’. They are very difficult to treat because they are capable of turning off target sites for common antibiotics, becoming up to 1,000 times less susceptible. In a significant proportion of cases, antibiotics have only a temporary effect and repeated grommet operations are needed.
First, the team produced a biodegradable pellet capable of doing the job. Dr Mat Daniel said: “We tested antibiotics against biofilms in the laboratory but it rapidly became apparent that very much higher levels of antibiotics would be needed. Because of that we knew that giving antibiotics by mouth was not going to work. We developed this biodegradable antibiotic pellet so we could put it directly into the ear — where the actual infection is. We hope that in the future this may very much reduce the need for any children to have more than one operation.”
Next, they found a way of demolishing the biofilm to make the infection easier to treat. This work has been the responsibility of Dr Saif Al-Zahid. He said: “Bacteria in biofilms are held together in a strong matrix. We have recently found that the expectorant N-Acetylcysteine is able to break down this biofilm matrix effectively — thereby releasing bacteria to a free-floating planktonic form. In doing so antibiotics become much more effective in killing bacteria as the protective properties of a biofilm are no longer present. N-Acetylcysteine has an added benefit due to its mucus reducing properties — this is desirable in glue ear as the middle ear is filled with a thick mucus secretion. As a result the addition of N-Acetylcysteine in our antibiotic pellet would be likely to increase the chance of eradicating middle ear biofilms and speed up the resolution of glue ear.”