1. Health Protection Agency, Centre for Infections, Respiratory and Systemic Infection Laboratory, London NW9 5HT, United Kingdom
2. Health Protection Agency, Heartlands Hospital, Birmingham B9 5SS, United Kingdom, and Division of Immunity and Infection, Medical School, University of Birmingham, Birmingham B15 2TT, United Kingdom
3. Health Protection Agency, Regional Epidemiology Unit, Health Protection Agency, Leeds, United Kingdom
4. Scottish Centre for Infection and Environmental Health, Glasgow G3 7LN, United Kingdom
5. Department of Veterinary Bacteriology, University of Glasgow Veterinary School, Glasgow, United Kingdom