Phenotypic characterisation of Pasteurella multocida strains isolated from rabbits in Poland

Pasteurella multocida is an important pathogen in many species of domestic and wild mammals, as well as birds. It is also a commensal in the nasopharynx of clinically healthy animals. The aim of the study was to characterise and classify field strains of P. multocida isolated from rabbits in Poland. A total of 115 field strains isolated from rabbits in 1999–2020 were used. The examined strains were evaluated morphologically and microscopically, and their ability to produce catalase and oxidase was determined. Identification of P. multocida strains was performed on basis of biochemical characteristics and serotype classification. Based on the biochemical profile assessment using API 20E and the ID 32E (bioMérieux), the strains isolated from rabbits were identified as P. multocida . Among 17.4% were classified as P. multocida subsp. multocida , 80% as ornithine decarboxylase negative P. multocida subsp. multocida and 2.6% as P. multocida subsp. septica . The capsule of type A was found in 87.8% of strains, type D in 8.7%, and type F in 3.5%. The somatic antigen of serotype 12 was present in 64.3% of strains, and serotype 3 in 36.7% of strains. The capsular type A was predominant among strains from rabbits that were asymptomatic carriers, while the capsular type D and F were found mainly in strains isolated from sick animals. In turn, the somatic antigen of serotype 12 was present in strains from both healthy and diseased animals, while strains of serotype 3 were much more frequently isolated from diseased rabbits. The conducted research allowed to classify and obtain new in-depth data on the population structure of P. multocida strains isolated from rabbits in Poland.