Actinobacillus is a genus of bacteria that are primarily known to inhabit the mouths and respiratory tracts of various animals, including humans. These bacteria are gram-negative and can be associated with several infections, particularly in livestock. Some species, like Actinobacillus pleuropneumonia, are known to cause serious diseases in pigs, leading to significant economic losses in the agricultural sector. In addition to their veterinary importance, certain Actinobacillus species can also affect humans, particularly in immunocompromised individuals. They are often studied in microbiology and veterinary medicine to understand their pathogenic mechanisms and develop effective treatments.