Air-flow resistances of silicone rubber voice prostheses after formation of bacterial and fungal biofilms

Laryngectomized patients use silicone rubber voice prostheses to rehabilitate their voice. However, biofilm formation limits the lifetime of voice prostheses by causing leakage or an increased air-flow resistance and the prosthesis has to be replaced. To determine which bacterial or yeast strains, isolated from explanted voice prostheses, contribute most to increases in air-flow resistance of silicone rubber voice prostheses, biofilms consisting of either a bacterial or a yeast strain were grown on voice prostheses in the artificial throat model. The effects of these biofilms on air-flow resistances were determined by calculating the difference in air-flow resistance of the individual voice prosthesis as covered with a 7-day-old biofilm with the situation prior to biofilm formation. Conspicuously, voice prosthetic biofilms formed by the bacterial strains Staphylococcus aureus GB 2/1 and Rothia dentocariosa GBJ 41/25B and their excreted organic matter showed larger increases in air-flow resistance (more then 30 cm H(2)O.s/L) than biofilms formed by Candida species. This is contrary to the literature, where there seems to be agreement that Candida species are mainly responsible for clinical failure of silicone rubber voice prostheses. (C) 2001 John Wiley & Sons, Inc

The influence of radiotherapy on the lifetime of silicone rubber voice prostheses in laryngectomized patients

Objectives: To establish a relationship between voice prosthetic lifetime in laryngectomized patients and the irradiation dose applied to the neck node levels (field of the neck) in which the major salivary glands are partially included. Furthermore, a possible relationship between voice prosthetic lifetime and the irradiation dose applied to the primary tumor site was studied. Study Design: A retrospective analysis was performed on 101 patients after laryngectomy. Methods: The records of 101 patients who underwent total laryngectomy between January 1993 and November 1999 at the Department of Otorhinolaryngology, University Hospital Groningen, The Netherlands, were analyzed. The following parameters were obtained: age, sex, radiotherapy, radiation fields, irradiation dose per field, tumor site, TNM classification, and valve insertion. Results: Irradiation to extensive neck fields, including the submandibular glands, did not influence the voice prosthetic lifetime after laryngectomy. However, primary tumor doses exceeding 60 Gray significantly shortened the mean voice prosthetic lifetime per patient. Conclusions: This study identified an association between radiation on the primary tumor site with a dose equal to or more than 60 Gray and limited lifetimes of voice prostheses

Influence of different combinations of bacteria and yeasts in voice prosthesis biofilms on air flow resistance

Laryngectomized patients use silicone rubber voice prostheses to rehabilitate their voice. However, biofilm formation limits the lifetime of voice prostheses. The presence of particular combinations of bacterial and yeast strains in voice prosthesis biofilms has been suggested to be crucial for causing valve failure. In order to identify combinations of bacterial and yeast strains causative to failure of voice prostheses, the effects of various combinations of bacterial and yeast strains on air flow resistances of Groningen button voice prostheses were determined. Biofilms were grown on Groningen button voice prostheses by inoculating so-called artificial throats with various combinations of clinically relevant bacterial and yeast strains. After 3 days, all throats were perfused three times daily with 250 ml phosphate buffered saline and at the end of each day the artificial throats were filled with growth medium for half an hour. After 7 days, the air flow resistances of the prostheses were measured. These air flow resistances were expressed relative to the air flow resistances of the same prostheses prior to biofilm formation. This study shows that biofilms causing strong increases in air flow resistance (26 to 28 cm water.s/l) comprised combinations of microorganisms, involving Candida tropicalis, Staphylococcus aureus and Rothia dentocariosa

Comparison of the microbial composition of voice prosthesis biofilms from patients requiring frequent versus infrequent replacement

This study was performed to establish a possible difference in biofilm composition in patients who require frequent versus infrequent prosthesis replacement. Only Groningen button voice prostheses that were removed because of increased airflow resistance or leakage of food or liquids through the prosthesis were considered for this study. These prostheses were selected from a total of 692 failed voice prostheses over a 2-year evaluation period. The failed voice prostheses were subdivided into a short-lifetime group, corresponding to an implantation period of less than 4 months (20 voice prostheses), and an extended-life time group, cor-responding to an implantation period of greater than 9 months (18 voice prostheses). The biofilm was removed from the valve sides of the prostheses. The bacterial strain Rothia dentocariosa and the yeast strains Candida albicans I and Candida tropicalis were the predominant strains isolated from the biofilms on the voice prostheses in the short-lifetime group, whereas in the extended-lifetime group, R dentocariosa was found with a fourfold lower isolation frequency and C albicans I was found with a twofold lower isolation frequency. Candida tropicalis was absent from the extended-lifetime group