1. Department of Animal Supply, National Institute of Public Health and Environmental Hygiene, P.O. Box, 3720 BA Bitthoven, The Netherlands; Department for Laboratory Animal Bacteriology, National Institute of Public Health and Environmental Hygiene,
P.O. Box, 3720 BA Bitthoven, The Netherlands
2. Central Animal Laboratory, Catholic University, Nijmegen, The Netherlands
3. Department of Animal Supply, National Institute of Public Health and Environmental Hygiene, P.O. Box, 3720 BA Bitthoven, The Netherlands
4. Department for Laboratory Animal Bacteriology, National Institute of Public Health and Environmental Hygiene, P.O. Box, 3720 BA Bitthoven, The Netherlands
5. Department for Laboratory Animal Science, Faculty of Veterinary Medicine, State University, Utrecht, The Netherlands
6. Central Institute for the Breeding of Laboratory Animals TNO Zeist, Catholic University, Nijmegen, The Netherlands
7. Department of Submicroscopical Morphology, Catholic University, Nijmegen, The Netherlands
8. Department of Medical Microbiology, State University Groningen, Nijmegen, The Netherlands
9. Department of Gastroenterology, Catholic University, Nijmegen, The Netherlands