1. The Veterinary Centre, 207 Daventry Road, Chevlesmore, Coventry, CV3 5HH, UK
2. Laboratory of Hospital Infection, Central Public Health Laboratory, Colindale Avenue, London, NW9 5HT, UK
3. Department of Microbial Diseases, St John's Institute of Dermatology, St. Thomas' Hospital, London, SE1 7 EH, UK