|pagebody = The ''Pasteurella'' and ''Mannheimia'' species are small, Gram-negative bacilli or coccobacilli. They are common commensals of the upper respiratory tract and gastrointestinal tract mucosa of animals. | |pagebody = The ''Pasteurella'' and ''Mannheimia'' species are small, Gram-negative bacilli or coccobacilli. They are common commensals of the upper respiratory tract and gastrointestinal tract mucosa of animals. |