Extending the life of voice prosthetics

19 June 2019

Researchers have been investigating the use of antifungals to extend the life of voice prosthetics.

A multi-disciplinary team including researchers from the Kent Fungal Group (University of Kent, UK) and Clinicians from the East Kent Hospital University Foundation Trust (EKHUFT) have been investigating the use of antifungals to prevent the failure of voice prosthetics.

Patients with laryngeal cancer may have to have a total laryngectomy. During this procedure the vocal cords are removed, leaving them unable to form speech. A small silicone valve known as a voice prosthesis can allow patients to speak again. However, these devices can be colonised by microbes and fail, leading to poor speech and increased risk of potentially life-threatening infection.

Voice prosthetics are susceptible to colonisation by microbial biofilms. Biofilms are formed when microbes come together and secrete sticky extracellular substances that protect them from factors such as temperature changes and antibiotics.

The main fugal species found to colonise voice prostheses is the yeast Candida albicans. This fungus is one of the species responsible for causing candidiasis, a fungal infection that can be fatal if contracted by immunosuppressed individuals.

If biofilms are left to grow, the valve becomes blocked and the prosthetics fail. On average, a prosthetic only lasts six months, and the patient needs to undergo an invasive procedure to replace the faulty prosthetic. Dr Campbell Gourlay from the University of Kent has been studying the main issues associated with colonisation of prosthetics and looking at potential treatments to increase their lifespan.

Using the findings of the research, Dr Gourlay’s team have collaborated with EKHUFT clinicians to develop a care routine for the prosthetics in conjunction with the NHS. The routine involves careful application of a small amount of antifungal directly onto the prosthetic. So far, this technique has significantly extended the lifespan of the devices and reduced the need for valve replacement.

Dr Gourlay has highlighted the importance of the research, saying: “We have demonstrated that application of a simple antifungal treatment regime prevents valve failure in most patients fitted with a voice prosthesis. This ensures that they are able to maintain speech, experience a reduced risk of chest infection and have an improved quality of life.”

To understand how to prevent biofilm formation on voice prosthetics, Dr Gourlay has been researching the ideal conditions required for C. albicans to grow. He has found that the high-carbon dioxide (CO2) content of exhaled air could be accelerating the formation of biofilms on voice prosthetics. Exhaled breath has 5% CO2 content, compared to 0.03% in normal air. The research has found that this elevated CO2 concentration accelerates biofilm production and adhesion, meaning voice prosthetics may be more at risk for biofilm formation than prosthetics in other parts of the body.

The care routine developed by Dr Gourlay and the EKHUFT multi-disciplinary team has been fully ratified by the NHS and is in use around the country.

Dr Gourlay will present his findings at the British Yeast Group: Discovery to Impact Focused Meeting in Newcastle. His talk An effective antifungal treatment strategy that significantly extends voice prosthesis lifespan in patients following total laryngectomy’ will take place at 15:20 on Wednesday 26 June.

Image: iStock/magicmine.