Development and epidemiological applications of a bacteriophage typing system for typing Pasteurella multocida.

A bacteriophage typing system was developed for typing toxigenic and nontoxigenic strains of Pasteurella multocida. A phage set of 24 phages with different lytic spectra was isolated after mitomycin treatment of P. multocida strains, isolated mainly from pigs from herds with atrophic rhinitis. On a test set of 97 different strains isolated from pigs, these 24 phages were able to type 87% of the strains. The 97 test strains could be subdivided into 31 different types by reaction with the 24 phages. The reproducibility after subculture and storage of the strains was good (95%). Phage typing of 217 toxigenic P. multocida field isolates from 37 pig herds predominately with clinically atrophic rhinitis resulted in 18 different phage types and an overall typability of 68%. Of 24 herds from which more than three isolates of toxigenic P. multocida were obtained, a single phage type was demonstrated in 5 herds, while in 9 herds a single phage type represented at least half of the isolates. The phage types in the remaining 10 herds revealed no dominating phage type. The phage typing system described appears to be a valuable epidemiological tool for studying the spread of P. multocida.