John Elmerdahl Olsen is Professor of Veterinary Microbiology at the School of Veterinary Medicine and Animal Science at University of Copenhagen. He obtained his PhD in Microbiology in 1989 based on studies of molecular epidemiology of Salmonella in Danish livestock. He became faculty member at the University in 1991. He has published more than 300 peer reviewed articles in international journals, dealing with pathogenicity, epidemiology, and detection of a wide range of veterinary important bacteria. Currently he works strategies to prevent resistance development, metabolic responses in E. coli to antimicrobial treatment, Salmonella host specificity mechanisms and E. coli pathotypes causing calf diarrhoea. His research is supported by the European Commission, The National Research Foundation Denmark, The Innovation Fund Denmark and the Danish Ministry for Food, Agriculture and Fisheries.