Development of an in Vitro Novel Device that Simulates the Real Life of the Biofilm Formation on Catheters under both Static and Continuous Fluid Flow Systems

Abstract

Biofilm model systems are essential to explore the development and the nature of the microbial community within the biofilm as well as the mechanism of their resistance. The aim of this work is to develop a simple in vitro novel device which mimics the real life of the biofilm formation and could be modulated to contain most catheter and tubes and readily allows biofilm formation under different experimental conditions. Two clinical isolates, Staphylococcus epidermidis and Candida albicans, were used to validate the device. The viability of the microorganisms within the biofilm was demonstrated quantitatively by viable count and semi-quantitively by using Scanning Electron Microscope and Confocal Scanning Laser Microscope. The shear stress on the inner and outer surfaces of the catheter was determined at different flow rates of the culture medium. The presented device supports biofilm formation of the tested microorganisms under static and dynamic fluid flow systems. The results are comparable to that of other biofilm models. The number of cells contained in the biofilm under static system was significantly higher than that of the biofilm which formed under dynamic system for both microorganisms. For S. epidermidis, the log value of the number of cells contained in the biofilm under static system was 6.41 ± 0.22 compared to 5.18 ±0.13 of the biofilm which formed under continuous fluid flow system (p < 0.001). For C. albicans, the log value of the number of adherent cells was 6.44 ± 38 and 5.47 ± 0.05 respectively (p = 0.012). The presented well suited to study the real life of the biofilm formation by microorganisms. It enables the formation of a reproducible biofilm of bacteria and yeast on the catheter surface in both static and dynamic systems and its design permits low laminar flow system.