Serotyping and antimicrobial resistance of Mannheimia haemolytica strains from European cattle with bovine respiratory disease.

The objective of this study was to assess the prevalence of three serotypes, A1, A2, and A6 in 98 M. haemolytica isolates collected from clinical BRD cases in European cattle and assess their antimicrobial resistance profiles. Isolates were characterized by serotyping (plate agglutination and serotype specific PCR) and antimicrobial susceptibility testing. The study identified a predominance of serotypes A1 (59%) and A6 (22%) in European M. haemolytica isolates exhibiting a relatively low level of antimicrobial resistance. A comprehensive understanding of the relative prevalence of different M. haemolytica serotypes in Europe informs a targeted approach for vaccine design against BRD.