engleski

Biofilm formation on voice prostheses

OBJECTIVES: The durability of voice prostheses after their implantation is variable, and the most frequent reason for replacing a voice prosthesis is leakage of fluids into the trachea due to valve insufficiency, which mainly is caused by biofilm formation. The purpose of the study was to determinate the presence of individual microorganisms and the most frequent microbial combinations in the biofilm of the indwelling voice prosthesis in situ. METHODS: The study was performed by retrospective analysis of data archived at medical documentation of the Clinical Medical Centre and the Teaching Institute of Public Health in Rijeka. Over a five-year period, voice rehabilitation in laryngectomized patients was performed by implanting a Provox2 voice prostheses (Atos Medical AB, Sweden). In total 100 implanted voice prostheses, at least one of every patient, were microbiologically processed immediately after being replaced. The biofilm was removed from the valve by scraping and rigorous homogenization in saline. The composition of the microflora found in the biofilm was determined by plating 0.1 mL of the homogenate on nutritional substrates for cultivation of fungi Sabouraud agar, chromagar Candida plate (CHROMagar™Candida, BD Diagnostics, USA), and the blood agar for the culture of bacteria. Identification of isolated strains was performed using standard laboratory protocols and commercial kits (API bioMerieux, France). RESULTS: Out of the total of 292 isolates, 67% were bacteria and the remaining 33% were yeasts. 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 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. CONCLUSION: Dividing the prostheses in 4 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.

Biofilm; voice prostheses; microorganisms

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