Escherichia (E.) coli is part of the intestinal flora. However, it can cause diarrhea in suckling and weaned piglets if the number of bacteria in the gut is increasing to higher levels and the strain is featuring certain virulence markers. Enterotoxins of E. coli interfere with mechanisms for the resorption of electrolytes and water and lead to a secretory diarrhea. Some strains have the ability to produce Shiga-toxins that cause edema disease. Additionally systemic infections can occur and systemic reactions to endotoxins are described. Hygiene and feeding management are imported factors to control the pathogen, but associated diseases are often treated or prevented by the use of antibiotics. Antibiotic sensitivity varies greatly among E. coli isolates and other authors are observing that the in vitro resistance to various antibiotics is dramatically increasing over the last several years. This study is analyzing the results of antibiotic sensitivity tests of E. coli isolates in Austria in the years 2007 - 2009.