Figure 1 Representative examples of the fluorescence 1 of E. coli ATCC 25922 after incubation with 0.01% acetic acid as vehicle (A) and biopsy extracts from patients with Crohn's disease (B) and ulcerative colitis (C). After cell damage or cell death the membrane potential sensitive dye [bis‐(1,3‐dibutylbarbituric acid) trimethine oxonol] (DiBAC₄(3)) enters the bacterial cells, leading to increased fluorescence 1.