Biofilm in voice prosthesis: A prospective cohort study and laboratory tests using sonication and SEM analysis

The objective of the study was to compare the biofilm growing pattern and its morphological extent on silicone and a teflon-like material using a sonication process and a Scanning Electron Microscope (SEM).

A prospective cohort study and a laboratory study.

Otolaryngology -Head and Neck surgery Department and the Microbiology Institute.

The participants included fifteen laryngectomised patients with phonatory prostheses, which were removed because of device failure, and two different kinds of phonatory prostheses from the laboratory (Provox 2 and ActiValve) that were artificially colonised by Candida albicans.

Tracheo-oesophageal puncture (TEP) is currently considered the gold standard for post-laryngectomy voice rehabilitation. "Leakage" represents the most common cause of substitution and is generated by biofilm colonisation of the prosthesis by mixed mycotic and bacterial agents. New biomaterials have been developed that are deemed to be more resistant to the colonisation of micro-organisms and material deformation.

The devices showed colonisation by mixed bacterial flora (Staphylococci 13%, Streptococci 9%, and Haemophilus influenzae 5%) and by yeasts (Candida albicans 12%). Moreover, we observed a different distribution of biofilm layers in Provox ActiValve (22.56%) compared to Provox 2 (56.82%) after experimental colonisation by the previously isolated Candida strain.

Resident microbiological species from the upper airways unavoidably colonise the polymer surfaces, and no strategies have been effective except for the manipulation of the chemical-physical properties of the device's polymer. Our study confirms that Provox ActiValve, which is made with a fluoroplastic material (teflon-like), is less subject to in vitro colonisation by Candida, and thus showed a higher clinical resistance to biofilm and a longer lifespan. The sonication seems to significantly improve the knowledge of bacterial and mycotic flora in biofilm colonisation. The design of a device for the daily cleaning capable to reach and brush the oesophageal flange of the prosthesis preserving the valve mechanism could represent a practical and simple help in this still unsolved problem.