The Probiotic E. coli Strain Nissle 1917 for the Treatment of Collagenous Colitis: First Results of an Open-Label Trial - Tromm, A ; Niewerth, U ; Khoury, M ; Baestlein, E ; Wilhelms, G ; Schulze, J ; Stolte, M (Zeitschrift für Gastroenterologie, 2004)