DUAL SPECIES BIOFILMS IN THE DIALYTIC ENVIRONMENT

Abstract

Purpose : Microorganisms can form conglomerates associated with a solid surface and embedded by an extracellular matrix of polysaccharides, called biofilms. Factors such as pH and oxygenation can modulate the co-aggregation between microorganisms of genera and even of different kingdoms, providing synergistic, competitive or antagonistic interactions. Although the standardizations for biofilm monitoring are non-existent, they have already been found in the hemodialysis microenvironment. This work proposes to evaluate the capacity of biofilms formation by Escherichia coli and Fusarium oxysporium , using isolates obtained in the water circuit of a Hemodialysis Service. Methods : The biofilms were formed in microplates (96 wells), in solutions that mimic the dialysis fluids, incubated at 37oC for 72 hours in both aerobic and microaerophilic conditions and quantified using the violet crystal methodology. Results : Dual species biofilms were observed in all solutions tested. Oxygenation did not interfere in the formation of biomass in the different fluids. The neutral pH found in the simple dialysate or it added of dextrose, proved to be the best fluid for the formation of biomass, where it was observed that the biomass of the dual species biofilms was equal to that of the monospecies biofilms. E. coli monoespecies biofilms formed lower biomass in acid solution. Fusarium biofilms monospecies formed less biomass in the basic solution. Conclusion : The dialysate may be a substrate for biofilm formation by the organisms tested, when associated or in monospecies biofilms. Good practices in handling patients, devices and environments are essential to control the microbial load in the dialysis environment.