Development of a typing system for epidemiological studies of porcine toxin-producing Pasteurella multocida ssp. multocida in Denmark

The aim of the present study was to evaluate capsular-typing, plasmid-profi ling, phage-typing and ribotyping for epidemiological studies of toxin-prod ucing Pasteurella multocida ssp. multocida in Denmark. The evaluation of me thods was based on 68 strains from nasal swabs and 14 strains from pneumoni c lungs. Strains from lungs were all of capsular Type A, whereas strains fr om nasal swabs were of both capsular Types A and D. Only 9% of the strains contained plasmids, which could not be associated with antibiotic resistanc e. Phage-typing divided 61% of strains into 10 groups, while 39% were non-t ypable. CfoI ribotyping divided strains into four groups of which one type contained 94% of isolates. HindIII ribotyping divided strains into 18 types . A total of 18 strains from The Netherlands, UK and USA were subjected to HindIII ribotyping, resulting in 13 types of which six were identical to ri botypes of Danish strains. Phage-typing of isolates from an outbreak of atr ophic rhinitis involving six herds in 1985 showed the existence of an epide mic strain. This type was recognised in the herd suspected of being the sou rce of the infections and in four of the five infected herds. These finding s were supported by HindIII ribotyping, as 85% of isolates from all herds w ere assigned to one ribotype. In conclusion, HindIII ribotyping seems to re present a useful tool for epidemiological studies of toxigenic P. multocida ssp. multocida. (C) 1999 Elsevier Science B.V. All rights reserved.