In vitro Inhibition of Biofilm Formation on Silicon Rubber Voice Prosthesis: Α Systematic Review and Meta-Analysis.

INTRODUCTION: Biofilm formation on voice prostheses is the primary reason for their premature implant dysfunction. Multiple strategies have been proposed over the last decades to achieve inhibition of biofilm formation on these devices. The purpose of this study was to assess the results of the available in vitro biofilm inhibition modalities on silicone rubber voice prostheses. METHODS: We conducted a systematic search in PubMed, Embase, and the Cochrane Central Register of Controlled Trials databases up to February 29, 2020. A total of 33 in vitro laboratory studies investigating the efficacy of different coating methods against Candida, Staphylococcus, Streptococcus, Lactobacilli, and Rothia biofilm growth on silicone rubber medical devices were included. Subgroup analysis linked to the type of prevention modality was carried out, and quality assessment was performed with the use of the modified CONSORT tool. RESULTS: Data from 33 studies were included in qualitative analysis, of which 12 qualified for quantitative analysis. For yeast biofilm formation assessment, there was a statistically significant difference in favor of the intervention group (standardized mean difference [SMD] = -1.20; 95% confidence interval [CI] [-1.73, -0.66]; p < 0.0001). Subgroup analysis showed that combined methods (active and passive surface modification) are the most effective for biofilm inhibition in yeast (SMD = -2.53; 95% CI [-4.02, -1.03]; p = 0.00001). No statistically significant differences between intervention and control groups were shown for bacterial biofilm inhibition (SMD = -0.09; 95% CI [-0.68, 0.46]; p = 0.65), and the results from the subgroup analysis found no notable differences between the surface modification methods. After analyzing data on polymicrobial biofilms, a statistically significant difference in favor of prevention methods in comparison with the control group was detected (SMD = -2.59; 95% CI [-7.48, 2.31]; p = 0.30). CONCLUSIONS: The meta-analysis on biofilm inhibition demonstrated significant differences in favor of yeast biofilm inhibition compared to bacteria. A stronger inhibition with the application of passive or combined active and passive surface modification techniques was reported.

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

OBJECTIVE: 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). DESIGN: A prospective cohort study and a laboratory study. SETTING: Otolaryngology -Head and Neck surgery Department and the Microbiology Institute. PARTICIPANTS: 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. MAIN OUTCOME MEASURES: 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. RESULTS: 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. CONCLUSION: 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.

Inhibition activity of Lactobacilli supernatant against fungal-bacterial multispecies biofilms on silicone.

Fungal-bacterial multispecies biofilms play a major role in failure of medical silicone devices, such as voice prostheses in laryngectomiy. In this study, we determined the effect of Lactobacilli supernatant (cell free) on mixed biofilm formation of fungi and bacteria on silicone in vitro. Lactobacilli supernatant inhibited the adhesion (90 min) of mixed fungi and bacteria species with an efficiency of >90%. Mixed biofilm formation and the metabolic activity of the biofilms were inhibited by 72.23% and 58.36% by Lactobacilli supernatant. The examination using confocal laser scanning microscopy and scanning electron microscopy confirmed that Lactobacilli supernatant inhibited the growth of mixed biofilm and damaged the cells. Moreover, Lactobacilli supernatant also inhibited Candida yeast-to-hyphal transition. Therefore, Lactobacilli supernatant may serve as a possible antibiofilm agent to limit biofilm formation on voice prostheses.

Biofilm on the tracheoesophageal voice prosthesis: considerations for oral decontamination.

The tracheoesophageal puncture (TEP) restores verbal communication after total laryngectomy using a one-way valved voice prosthesis (VP). Microbial colonization can shorten VP device life. Our aims were to investigate patterns of prosthetic and oral colonization, and record changes in VP device life after targeted decontamination. We conducted a retrospective review of TEP clinic patients who underwent microbial analysis of the VP between 01/2003 and 07/2013. Two subgroups were analyzed: (1) patients with microbial analysis of the VP and the mouth were analyzed to identify patterns of common contamination, and (2) patients who were prescribed targeted oral decontamination on the basis of the microbial analysis of the VP were analyzed to evaluate effects on device life. Among 42 patients, 3 patients had only fungal, 5 only bacterial, and 33 had polyspecies fungal and bacterial colonization. In the TEP-oral microflora subgroup (n = 15), 7 had common microorganisms in the mouth and on the VP. Among the decontamination subgroup (n = 23), 6 patients received broad spectrum rinse, 16 antifungal agents and 13 antibiotics, or a combination thereof. After targeted decontamination, the median device life of prostheses improved from 7.89 to 10.82 weeks (p = 0.260). The majority of patients with a suboptimal VP device life in this pilot had polyspecies bacterial and fungal colonization. VPs rarely had fungal contamination alone (3 %), and non-albicans fungal species were more common than expected. For these reasons, we are exploring the use of targeted decontamination regimens that were associated with 1.4-fold improvement in VP duration.

Voice prostheses, microbial colonization and biofilm formation.

Total laryngectomy is performed in advanced laryngeal and hypopharyngeal cancer stages and results in reduced quality of life due to the loss of voice and smell, permanent tracheostoma and occasionally dysphagia. Therefore, successful voice rehabilitation is highly beneficial for the patients' quality of life after surgery. Over the past decades, voice prostheses have evolved to the gold standard in rehabilitation and allow faster and superior voicing results after laryngectomy compared to esophageal speech. Polyspecies biofilm formation has become the limiting factor for device lifetimes and causes prosthesis dysfunction, leakage and in consequence pneumonia, if not replaced immediately. Although major improvements in prosthesis design have been made and scientific insight in the complexity of biofilm evolution and material interaction progresses, the microbial colonization continues to restrict device lifetimes, causing patient discomfort and elevated health costs. However, present scientific findings and advances in technology yield promising future approaches to improve the situation for laryngectomized patients.

[A review of the complications and candida colonization associated with voice rehabilitation using a voice prosthesis].

Between December 2004 and December 2011, we have used the indwelling voice prosthesis for voice rehabilitation in 28 patients after total laryngectomy in our department. To clarify both the complications and safety of voice reconstruction using a voice prosthesis, and the occurrence of candida colonization, we conducted a retrospective study with a review of the Japanese literature. Twenty-six patients who were observed over a period of more than six months at our hospital were enrolled in this study. We examined the interval of prosthesis replacement, types and frequency of complications, candida colonization, and clinical outcomes. The median follow-up time postoperatively was 28.8 months (range 8.1-95.7). The average interval of prosthesis replacement was 147 days (4.9 months). Complications occurred in 14 patients (54%), and 6 patients (23%) of whom were hospitalized. The main complications were periprosthetic leakage, increased granulation around the tracheoesophageal shunt and stenosis of the trachea stoma. There were no significant differences in the frequency of complications in the background factor of the patients as far as age (p = 0.495), radiation therapy (p = 0.686) or reconstruction time (p = 0.257) were concerned. Candida species was detected in 81% of the specimens which we submitted to a culture test and confirmed the pseudohyphae which comfirmed the pathogenicity from the histopathological examination. Moreover, radiation therapy was significantly associated with the detection of candida (p = 0.004). Permanent closure of the tracheoesophageal shunt for periprosthetic leakage was required in one patient, but we were able to deal with the other complications. No patient experienced any life-threatening complications and all are safely using the prostheses. It has been reported that complications will occur over the long-term, thus careful follow-up is necessary.

[The use of the lactate-fortified milk whey for the prolongation of the functional life of the voice prostheses].

The objective of the present study was to develop the method for the prolongation of the functional life of the voice prostheses in the patients who underwent laryngectomy with special reference to the decrease of the risk of mycotic infection in the laryngo-oesophageal region. The original method is proposed with the application of the lactate-fortified milk whey that makes it possible to maintain the high concentration of living lactic acid bacteria in the laryngo-oesophageal segment where the voice prosthesis is located. The method was tested on 73 patients. It permitted to significantly prolong the functional life of the voice prostheses (from 12 to 20 months) and prevent mycotic infection. It is concluded that the proposed method promotes the improvement of the patients' quality of life following laryngectomy for the treatment of cancer.

Oral microbial colonization in laryngectomized patients as a possible cofactor of biofilm formation on their voice prostheses.

AIM: Biofilm formation on voice prostheses, which are used for voice rehabilitation in laryngectomized patients, is a main cause of device failure. The aim of this study was to assess whether the presence of periodontal pathogens in the biofilm on voice prostheses is related to that in the oral cavity and associated with the periodontal status of the patients. METHODS: Thirty-one laryngectomized patients were invited to participate, 13 of whom met exclusion criteria. The remaining 18 were classified according to the community periodontal index of treatment needs (community periodontal index of treatment needs (CPITN), grades 0-4). Biofilm samples from the oral cavity and voice prostheses were analysed by PCR-based hybridization for 11 pathogens. RESULTS: All dentate patients required periodontal treatment (CPITN-3: n = 4, CPITN-4: n = 8); the remaining six were edentulous. The diversity (i.e. number of bacterial species detected) of pathogens detected on the voice prostheses correlated significantly positively with the diversity of pathogens in the oral cavity and with clinical parameters. Furthermore, the diversity of pathogens differed significantly between dentate and edentulous patients. CONCLUSIONS: Results emphasize the oral cavity as an important source of bacteria for biofilm formation on voice prostheses. Whether these pathogens reduce the lifetime of the device by increased biofilm formation and/or increase the risk of silicone deterioration requires further study.

Effect of silver sulfadiazine on mature mixed bacterial biofilms on voice prostheses.

BACKGROUND: Biofilm formation on voice prostheses disrupts the function and limits the lifespan of voice prostheses. There is still no effective clinical strategy for inhibiting or removing these biofilms. Silver sulfadiazine (SSD), as an exogenous antibacterial agent, has been widely used in the prevention and treatment of infection, however, its effect on voice prosthesis biofilms is unknown. The purpose of this study was to explore the effect of SSD on the mature mixed bacterial biofilms present on voice prostheses. METHODS: Quantitative and qualitative methods, including the plate counting method, real-time fluorescence quantitative PCR, crystal violet staining, the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) (XTT) reduction assay, scanning electron microscopy, and laser confocal microscopy, were used to determine the effect of SSD on the number of bacterial colonies, biofilm formation ability, metabolic activity, and ultrastructure of biofilms in a mature mixed bacterial (Staphylococcus aureus, Streptococcus faecalis and Candida albicans) voice prosthesis biofilm model. The results were verified in vitro on mature mixed bacterial voice prosthesis biofilms from patients, and the possible mechanism of action was explored. RESULTS: Silver sulfadiazine decreased the number of bacterial colonies on mature mixed bacterial voice prosthesis biofilm, significantly inhibited the biofilm formation ability and metabolic activity of mature voice prosthesis biofilms, inhibited the formation of the complex spatial structure of voice prosthesis biofilms, and inhibited the synthesis of polysaccharides and proteins in the biofilm extracellular matrix. The degree of inhibition and removal effect increased with SSD concentration. CONCLUSIONS: Silver sulfadiazine can effectively inhibit and remove mature mixed bacterial voice prosthesis biofilms and decrease biofilm formation ability and metabolic activity; SSD may exert these effects by inhibiting the synthesis of polysaccharides and proteins among the extracellular polymeric substances of voice prosthesis biofilms.

Yeast colonization of voice prostheses: pilot study investigating effect of a bovine milk product containing anti-Candida albicans immunoglobulin A antibodies on yeast colonization and valve leakage.

OBJECTIVES: Our goals were to determine whether a bovine milk product containing anti-Candida albicans immunoglobulin A antibodies ("immune milk") could reduce the adherence of C albicans to voice prosthesis silicone in vitro, and whether administration of the milk could reduce C albicans colonization and voice prosthesis damage in vivo. METHODS: An in vitro assay of C albicans attachment to silicone was developed with radiolabeled C albicans. A pilot crossover in vivo trial, over 3 periods of 3 months, was also undertaken for 4 patients with voice prostheses, comparing daily administrations of immune milk and a control milk product. The prosthesis valves were replaced at each changeover and were assessed for wet weight of removable biofilm, yeast numbers in removable biofilm, valve leakage, and valve damage. RESULTS: Immune milk inhibited C albicans adherence to silicone in vitro. However, in a small clinical pilot study, this effect was not replicated. CONCLUSIONS: There is scope to further investigate the topical use of immune milk for management of voice prosthesis biofilms.

Biofilms on tracheoesophageal voice prostheses: a confocal laser scanning microscopy demonstration of mixed bacterial and yeast biofilms.

The aim of this study was to demonstrate the presence of yeast and bacterial biofilms on the surface of tracheoesophageal voice prostheses (TVPs) by a double-staining technique with confocal laser scanning microscopy (CLSM). Biofilms of 12 removed TVPs were visualized by scanning electron microscopy, then stained with ConA-FITC and propidium iodide for CLSM. Microbial identification was by partial 16S rRNA gene analysis and ITS-2 sequence analysis. Microbial biofilms on the TVPs consisted of bacteria and filamentous cells. Bacterial cells were attached to the filamentous and unicellular yeast cells, thus forming a network. Sequence analyses of six voice prostheses identified the presence of a variety of bacterial and yeast species. In vivo studies showed that Klebsiella oxytoca and Micrococcus luteus efficiently attached to Candida albicans. CLSM with double fluorescence staining can be used to demonstrate biofilm formations composed of a mixture of yeast and bacterial cells on the surface of TVPs.

Microbial colonization of tracheoesophageal voice prostheses (Provox2) following total laryngectomy.

The purpose of this study was to determine the presence of individual microorganisms and the most frequent microbial combinations in the biofilm of the indwelling Provox2 voice prosthesis in situ. Furthermore, we wanted to evaluate the possible influence of biofilm composition on the mean and median lifetime of these voice prostheses. Over a 5-year period, implantation of a Provox2 voice prosthesis was performed in 85 patients, or 90% of the overall number of patients who underwent total laryngectomy. In total 100 implanted voice prostheses, at least one of every patient, were microbiologically processed immediately after being replaced. Out of the total of 292 isolates, 67% were bacteria and the remaining 33% were yeasts. The most frequently found yeast species on voice prostheses biofilms was C. albicans, followed by C. krusei and C. tropicalis. The most frequently isolated bacteria included Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, and Streptococcus agalactiae. Simultaneous presence of bacteria and fungi was established in 83% of the processed voice prostheses; in 16% of samples the biofilm contained only one or more bacterial species. The mean time of implantation was 238 days and the median lifetime of the device was 180 days. Dividing the prostheses in four groups according to the composition of biofilm revealed that the device lifetimes varied significantly between groups. The longest lifetime of voice prostheses was associated with the presence of single fungal isolate in combination with bacteria. There is a significant correlation between biofilm composition and the device life time.

[Time course of microbial colonization of different voice prostheses]. / Die mikrobiologische Oberflächenbesiedlung verschiedener Stimmprothesenarten in der Zeitkinetik.

OBJECTIVE: For the vocal rehabilitation of laryngectomized patients, voice prostheses are actually one of the best known methods. Caused by the surface colonisation with bacteria and fungi the life time of the prostheses is limited to 3-4 months. MATERIAL AND METHODS: In a time period of 127 months we analysed the surface colonisation of 118 voice prostheses. RESULTS: The mean life time of the prostheses was 156 days. In reference to the prosthesis model we also recorded different times of usage (ESKA-Herrmann 141, Provox 2 184 and Provox 1 204 days (p>0.05)). In the microbiological examination the dominating bacteria were S. aureus, Klebsiella sp. and Proteus sp. It was possible to cultivate all these bacteria on every type of prosthesis used in the study. In addition C. albicans, C. glabrata, C. krusei and C. tropicalis were the main fungi on the silicone surface. Thereby a more frequent colonisation with C. krusei on ESKA-Herrmann prostheses was measured, caused by the bigger contact area with saliva on this model (p=0.034). CONCLUSIONS: Because of the similar position and way of function, all types of voice prostheses are colonized by almost the same species of bacteria and fungi. But in dependency of the type an affinity of individual species to special prostheses exist. The knowledge of these individual affinities is necessary for the further development of voice prostheses. Furthermore the diversity of bacteria and fungi species showed a level of saturation on the surface. This is caused by the limited space on the silicone prostheses.

[Candida biofilm formation on Provox 2 and Provox Acti Valve voice prosthesis]. / Tworzenie biofilmu candida na protezach glosowych Provox 2 oraz Provox Acti Valve.

INTRODUCTION: Patients who underwent laryngectomy due to larynx cancer have a possibility to regain ability to speak with the use of silicone voice prosthesis. However, the lifetime of the device is limited, and last for approximately 3-6 months, mainly due to bacterial and fungal biofilm formation, that subsequently causes deterioration of the prosthesis and malfunction of the valve mechanisms. Moreover, the biofilm can be reservoir for chronic and systemic infections. AIM: The aim of the following study was to investigate Candida biofilm formation on silicone voice prosthesis. MATERIAL AND METHODS: Experiments were performed using C. albicans and C. krusei fungal strains with Provox 2 and Provox Acti Valve voice prosthesis. Fungal biofilms were examined under various magnifications using SEM technique. RESULTS: Scanning electron microscopy revealed that Candida biofilms formed on voice prosthesis had highly heterogeneous structure and were composed of blastospores, pseudohyphae, hyphae and ,,germ tubes" encased in an extracellular material. Noticeable differences in biofilms structure depended on Candida species and type of voice prosthesis. CONCLUSIONS: Presented data throws light on problems concerned fungal colonization on indwelled medical devices.

Candida biofilm analysis in the artificial throat using FISH.

Biofilm formation is a common complication of the use of prosthetic devices. In clinical settings, biofilms can be comprised of one or more microbial species. In order to investigate the interaction between different species within a biofilm, a reproducible, reliable model system has to be utilized and an appropriate system for species identification applied. The present chapter describes the artificial throat model, a model system for growing mixed species biofilms on shunt prostheses. The model is used in conjugation with fluorescent in situ hybridization (FISH), which facilitates identification and localization of the resident microorganisms within biofilms.

[Examination of biofilm related material deterioration on 20 PROVOX2 voice prostheses by scanning electron microscopy]. / Elektronenmikroskopische Untersuchungen zur Biofilmbildung auf 20 PROVOX2 Stimmventilen.

BACKGROUND: Mechanical impairment of valve function by biofilms is considered to cause loss of function of voice prostheses in laryngectomized patients. Material deterioration and infiltrative growth of Candida associated biofilms have already been observed on Groningen Buttons. Goal of the study was the examination of biofilm formation and material damages on PROVOX2 voice prostheses. METHODS: 20 PROVOX2 voice prostheses were withdrawn from 17 laryngectomized patients due to aspiration (mean in-vivo time: 118 d, median 98 d). Microbial spectrum, colonization patterns and morphologies of prosthesis damage were assessed using standard microbiologic procedures and scanning electron microscopy. RESULTS: Biofilm with various growth patterns predominantly adhered to the esophageal parts of the prostheses. Microbiologic findings showed Candida species as main colonisers on esophageal surfaces. Different morphologies of surface alteration and material infiltration of the polymer material were identified on 8 prostheses with 35 d of in-vivo time minimum. CONCLUSION: Valve dysfunction of PROVOX2 voice prostheses can be attributed to biofilm formation on esophageal surfaces and edges of the valve flap and seating. The identified morphologies of material damage and invasive growth indicate towards lytic processes of the polymer material due to Candida associated biofilms.

Growth Media for Mixed Multispecies Oropharyngeal Biofilm Compositions on Silicone.

AIMS: Microbial colonization of silicone voice prostheses by bacteria and Candida species limits the device lifetime of modern voice prostheses in laryngectomized patients. Thus, research focuses on biofilm inhibitive properties of novel materials, coatings, and surface enhancements. Goal of this in vitro study was the evaluation of seven commonly used growth media to simulate growth of mixed oropharyngeal species as mesoscale biofilms on prosthetic silicone for future research purposes. METHODS AND RESULTS: Yeast Peptone Dextrose medium (YPD), Yeast Nitrogen Base medium (YNB), M199 medium, Spider medium, RPMI 1640 medium, Tryptic Soy Broth (TSB), and Fetal Bovine Serum (FBS) were used to culture combined mixed Candida strains and mixed bacterial-fungal compositions on silicone over the period of 22 days. The biofilm surface spread and the microscopic growth showed variations from in vivo biofilms depending on the microbial composition and growth medium. CONCLUSION: YPD and FBS prove to support continuous in vitro growth of mixed bacterial-fungal oropharyngeal biofilms deposits over weeks as needed for longterm in vitro testing with oropharyngeal biofilm compositions. SIGNIFICANCE AND IMPACT OF STUDY: The study provides data on culture conditions for mixed multispecies biofilm compositions that can be used for future prosthesis designs.

Long-term results of Provox ActiValve, solving the problem of frequent candida- and "underpressure"-related voice prosthesis replacements.

OBJECTIVES: To assess the long-term results of the Provox ActiValve, a prosthesis for voice rehabilitation after total laryngectomy that was designed to lessen the need for frequent replacements caused by Candida and "underpressure." PATIENTS AND METHODS: Retrospective assessment of device lifetime, indications for replacement, voice quality, and maintenance issues, measured by a structured trial specific questionnaire, in a cohort of 42 laryngectomized patients, experiencing a short Provox2 device lifetime (median, 21 days). RESULTS: The median device lifetime of Provox ActiValve, replaced for leakage through the device and those still in situ at the date of data collection (N = 32), was 337 days (mean 376 days): a statistically significant 16-fold increase compared to the Provox2 prosthesis (P < .001). In 10 patients, replacement was fistula-related (median after 86 days): esophageal pouch (N = 4), fistula granulation (N = 3), extrusion of the device (N = 2), and periprosthetic leakage (N = 1). Eighty-six percent of the patients used a special lubricant to diminish "stickiness" of the valve. Provox ActiValve was preferred by 90% of the patients who completed the trial-specific questionnaire. CONCLUSIONS: For patients requiring frequent device-related replacements, Provox ActiValve, also long-term, provides a true solution and thereby is a valuable addition to prosthetic voice rehabilitation.

In vitro biofilm growth on modern voice prostheses.

BACKGROUND: Biofilm formation on voice prostheses in laryngectomized patients usually limits the lifetime of the device. The purpose of this study was to compare the biofilm resistance of different valve flaps of modern voice prostheses in an in vitro simulation of an oropharyngeal biofilm. METHODS: Growth of biofilm deposits on valve flaps (n = 12) removed from Provox 2, Provox Vega, Provox ActiValve, Blom Singer Advantage, and Phonax voice prostheses was evaluated and compared to medical-grade silicone (n = 12) in an in vitro biofilm model (22 days) after incubation with a multispecies bacterial-fungal biofilm composition. RESULTS: The Provox ActiValve and the Blom Singer Advantage prostheses showed significantly less surface biofilm formation than the other prostheses and then silicone. CONCLUSION: The use of silver oxide and Teflon as valve flap materials proves to reduce long-term biofilm formation in vitro. The applied model allows rapid screening for novel biofilm-inhibitive materials and durable coatings designated for more biofilm resistant medical devices.

Lactobacilli: important in biofilm formation on voice prostheses.

OBJECTIVE: We sought to identify bacterial strains responsible for biofilm formation on silicone rubber voice prostheses. STUDY DESIGN: We conducted an analysis of the bacterial population in biofilms on used silicone rubber voice prostheses by using new microbiological methods. METHODS: Two microbiological methods were used: polymerase chain reaction-denaturing gradient gel electrophoresis and fluorescence in situ hybridization. Twenty-six Provox2 and eight Groningen Ultra Low Resistance voice prostheses that were removed because of leakage through the prosthesis or because of increased airflow resistance were used in this study. RESULTS: The results showed that 33 of the 34 explanted voice prosthetic biofilms contained lactobacilli in close association with the Candida sp. present. CONCLUSION: Lactobacilli are general colonizers of tracheoesophageal voice prostheses in vivo, growing intertwined with Candida. This knowledge may be important in the development of new pathways directed to prevent or to influence biofilm formation on tracheoesophageal voice prostheses and elongate their lifespan.