Treating bacterial infections with antibiotics often kills intestinal flora, leading to diarrhoea and inflammation of the gut. Often it is bacteria known as Clostridium difficile which are responsible; they proliferate when the normal microbiome is killed by antibiotics. A working group headed by Professor Dr. Dr. Klaus Aktories of the Institute of Experimental and Clinical Pharmacology at the University of Freiburg, collaborating with Professor Dr. Andreas Schlosser of the Rudolf Virchow Center in Würzburg, has shown how the microbes’ poisonous proteins penetrate intestinal cells. The results of their study are published in the Proceedings of the National Academy of Sciences.