An in-vitro dynamic flow model for translational research into dental unit water system biofilms

Publication date: Available online 24 February 2020Source: Journal of Microbiological MethodsAuthor(s): Michel A. Hoogenkamp, Bernd W. Brandt, Johannes J. de Soet, Wim CrielaardAbstractDental unit water systems (DUWS) provide an excellent environment for biofilm formation and can form a potential health risk for patients and staff. To control this biofilm formation, better understanding of the DUWS biofilm ecology is needed. Described is a newly developed in-vitro DUWS model which is easy to build, can be inoculated with different water sources and allows for sampling of both the effluent and biofilm. Unlike most models, a dynamic flow pattern, typical for a dental unit is used to provide water as a nutrient source. Microbial growth and composition were analyzed using heterotrophic plate counts (HPC) and 16S rDNA sequencing. Growth was reproducible in all models, reaching quasi-steady state at day 16 in the effluent (105–106 CFU∙ml−1) and day 23 in the biofilm (108 and 107 CFU∙cm−2) for non-potable and potable water, respectively. Principal component analysis of the microbial composition showed that biofilms originating from either non-potable or potable water were significantly different after 30 days of growth (n = 8, PERMANOVA, F = 35.6, p < .005). Treatment of the biofilms with 1000 ppm active chlorine showed a biological and statistical significant decrease in viable counts in the effluent phase to below the detection limit of 100 CFUâ...
Source: Journal of Microbiological Methods - Category: Microbiology Source Type: research