The Pasteurellaceae are a family of Proteobacteria, given their own order. Most members live as commensals on mucosal surfaces of birds and mammals, especially in the upper respiratory tract. The family includes several pathogens of vertebrates, most notably Haemophilus influenzae. This species causes several diseases in humans (though not the flu, as was originally thought) and was the first organism to have its genome sequenced. Other human Pasteurellaceae cause gingivitis and chancroid, and many others are important veterinary pathogens.
Like other Proteobacteria, the Pasteurellaceae have Gram-negative stains. They are typically rod-shaped, and are a notable group of facultative anaerobes. They can distinguished from the related Enterobacteriaceae by the presence of oxidase, and from most other similar bacteria by the absence of flagella.
Bacteria in the family Pasteurellaceae have been classified into a number of genera based on metabolic properties, but these classifications are not generally accurate reflections of the evolutionary relationships between different species.