Actinobacillus suis

Also known as: A.suis, Actinobacillosis, A. equuli in swine, Actinobacillus suis septicaemia in horses, Actinobacillus suis septicaemia in pigs, Acute haemorhagic pulmonary infarction and necrotizing pneumonia in horses, Otitis media, externa, interna, middle and inner ear infections.

Scientific Classification
Kingdom	Bacteria
Phylum	Proteobacteria
Class	Zymobacteria
Sub-class	Alphaproteobacteria
Order	Pasteurellales
Family	Pasteurellaceae
Genus	Actinobacillus
Species	Actinobacillus suis

Introduction

A.suis is a beta-haemolytic Gram-negative bacterium. Strains of A.Suis vary due to differences in their lipopolysaccharides (LPS), which is known as the 'O' antigen and is referred to as O1,O2 and O3 and capsules (CPS), called 'K' antigen with variants described as K1, K2 and K3. It causes Actinobacillosis in pigs, horses, cattle and can infect [[Actinobacillus suis#signalment| various other species.

A.suis have genes that encode toxins similar to apxI and apxII of A. pleuropneumoniae, but are less virulent as they produce less Apx toxins than A. pleuropneumoniae. Once an animal is infected with A.suis it can provide partial cross protection against A. pleuropneumoniae.

Signalment

A.Suis can be found worldwide in both healthy and diseased animals which are genetically and biochemically similar. It is believed to be spread via aerososl infection and invasion of the upper respiratory tract. Wild hosts include anatidae (ducks, geese and swans) and Coypu but A.suis can also affect domestic species including pigs, horses, cattle, sheep, goats, alpacas, zebu, dogs, and cats.