 Several retrospective and prospective studies suggest that antibiotics increase the risk of HUS by release of Stx during bacterial lysis but also to certain types of antibiotics, increased synthesis of Shiga toxin. The meta-analysis performed by Wang et al on the use of antibiotics in patient with STEC diarrhea and DHUS highlighted an increased risk of developing DHUS in patients treated with antibiotics Wang et al. 2000. A second meta-analysis bringing together 20 studies, that compared the risk of HUS occurrence in patients with STEC diarrhea treated or not with antibiotics, has not concluded Panos et al. 2006. According to these results, antibiotherapy is actually not recommended for patients with diarrhea EHEC and patients with DHUS Scheiring et al. 2008. However, these studies did not distinguish between different classes of antibiotics, bringing together all the bacteriostatic antibiotics as well as bactericidal. But, in vitro studies have clearly shown that certain classes of antibiotics such as quinolones induced the production of Shigatoxin multiplying production by a factor of 100 for ciprofloxacin while others had a strong inhibitory action as the azithromycin Ohara et al. 2002 . 