uPVC coupon covered with H. pylori biofilm and variation of H. pylori numbers in the mono-species biofilm. Microphotograph of an uPVC coupon visualized under EDIC microscopy covered with a mono-species H. pylori biofilm after 1 day (a) and 32 days (b) of incubation. Black arrow indicates the presence of a microcolony. Bars represent 20 μm. (c) Variation with time in the total cell number (black diamond) and H. pylori PNA-cells (grey square) present in the biofilm. Bars represent standard deviation (n = 3).