PHENOTYPIC AND GENOTYPIC CHARACTERS OF ISOLATES OF PASTEURELLA-MULTOCIDA OBTAINED FROM BACKYARD POULTRY AND FROM 2 OUTBREAKS OF AVIAN CHOLERA IN AVIFAUNA IN DENMARK

Two outbreaks of fowl cholera in the avifauna in Denmark, affecting pr imarily elders but also cormorants, gulls and oyster-catchers were sho wn to be caused by the same clone of Pasteurella multocida ssp, multoc ida by restriction enzyme analysis (REA) and ribotyping, using the enz ymes HpaII and HhaI and phenotypic characterization. This observation indicated spread by migratory birds. It was shown that the outbreak cl one was closely related to isolates of Pasteurella multocida ssp, mult ocida obtained from back-yard poultry in Denmark, including chickens, pheasants, turkeys and ducks. The only detectable difference between t he outbreak clone and some of these strains concerned the size of one fragment. These results indicate a possible exchange of P. multocida s sp, multocida between populations of wild birds and back-yard poultry. Among the DNA fingerprinting methods used, restriction enzyme analysi s offered the highest discrimination among thirty strains obtained fro m back-yard poultry, The restriction enzymes HpaII and HhaI generated almost the same number of profile types, 17 and 15 respectively, but o nly HpaII differentiated the outbreak clone from the group of closely related strains isolated from back-yard poultry. Ribotyping, using the same enzymes, resulted in 12 and 10 different profile types, respecti vely. The outbreak isolates did not harbour any plasmids, while six ou t of the 30 strains originating from back-yard poultry (20%) carried a cryptic plasmid of approximately 3.4 kb.