mannheimia varigena mannheimia varigena mannheimia varigena is a bacterium, predominantly encountered in ruminants and historically classified within the former bacterial pasteurella haemolytica complex, a group of bacteria involved in bovine respiratory disease (brd) . it is pathogenic. mannheimia varigena scientific classification domain: bacteria phylum: pseudomonadota class: gammaproteobacteria order: pasteurellales family: pasteurellaceae genus: mannheimia species: m. varigenaangen et al. 1999