The purpose of this study is to determine whether the mix of microbial species isolated from biofilm-clogged voice prostheses is specific to each participant, whether the microbes are orally-derived and whether the presence of specific species is a predictor of the frequency with which patients discard devices due to malfunction. The microbes isolated from discarded devices will be used to test the antimicrobial properties of newly-developed medical silicones.

This study has three primary objectives and one secondary objective:

Primary Objectives

• To understand variation in the composition of mixed-species biofilms on voice prostheses, both between patients and over time within patients. This will enable us to target resistance to specific microbes using chemistry-based approaches in the design of new medical silicones and develop realistic in vitro models using relevant clinical isolates with which to test them.
• To explore the association between the incidence of specific microbes in biofilms, patient factors (use of antimicrobials, antacids and dentures), and increased device-replacement frequency.
• To explore whether the colonising microbes originate from the participants's oral flora.

Secondary Objective

• To study the interactions that occur within the social group of microbes isolated from each voice prosthesis to learn a) whether these species are interdependent, b) whether they cooperate with each other in order to build biofilms and b) which species produce compounds that physically degrade medical polymers.

STUDY DESIGN

Four hypotheses will be addressed by this study:

1. There is a correlation between the presence of certain microbes, or mixes of microbes, and the frequency of device replacement;
2. The source of the problem microbes is the participants's oral flora;
3. Participant-related factors such as continuous exposure of the microbes to antimicrobial or antacid treatments, or the use of dentures, may alter the composition of device biofilms.
4. Identification of problem microbes may assist in the development of new medical silicones that are specifically designed to resist these species.

These hypotheses will be addressed by collection of discarded devices from participants who are users of voice prostheses and registered at the Speech and Voice Clinic, Aberdeen Royal Infirmary (up to 27 people). Participants will be requested to donate discarded devices, mouthwash samples and simple data on recent antimicrobial or antacid treatments, and the use of dentures. The microbes colonising prostheses and contained within mouthwash samples will be isolated and identified and the association between microbial species and patient data over time will be analysed. Microbes will be stored as clinical isolates and used to test biofilm establishment and maintenance on silicones with modified surfaces designed to reduce biofouling.

Inclusion Criteria:

• Total larygectomy patients.
• Must be registered at Speech and Voice Clinic, Aberdeen Royal Infirmary

Exclusion Criteria:

• Under 18 years of age

Users of voice prostheses who are registered at the Speech and Voice Clinic, Aberdeen Royal Infirmary.

No individual patient data are available to the study