Actinobacillus suis
Also known as: A.suis
| 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 are known as 'O' antigens and are referred to as O1,O2 and O3 and capsules (CPS), refered to as'K' antigen with variants described as K1, K2 and K3. More than 95% of A. suis clinical isolates are cross-reactive with O1/K1 or O2/K3 antiserum and more severe infection were noted with O2/K2 srain [1]. This opportunistic bacteria mainly causes actinobacillosis in pigs, but has also been linked to neonatal calf pneumonia and localised infections, airsaculitis in waterfowl, and polyarthritis in alpacasand, to septicaemia, acute haemorrhagic pulmonary infarction and necrotizing pneumonia in horses and various other species.
Other haemolytic strains of Actinobacillus species have been linked to various diseases in horses such as Actinobacillus equuli and Actinobacillus ligneresii. The latter species also causes wooden tongue in cattle.
A.suis have genes that encode toxins similar to apxI and apxII of A. pleuropneumoniae, but they are less virulent. Once an animal is infected with A.suis it can provide partial cross protection against A. pleuropneumoniae. A.suis strains are able to resist bile and serum.
Signalment
A.Suis can be found in the tonsils and upper respiratory tract of both healthy and diseased pigs, and isolates are genetically and biochemically similar. It is believed to be spread via aerososl infection and invasion of the upper respiratory tract. The incidence of the disease is increasing, especially in North American high-health-status herds.
Wild hosts include anatidae (ducks, geese and swans) and Coypu but A.suis can also affect domestic species including pigs, cattle, sheep, goats, alpacas, zebu, dogs, cats and tentive links to equine disease have been recorded (although this is thought to be be an A.suis-like microorganism rather than A.suis itself).
Diagnosis
A.Suisis difficult to culture and most of the O1 strains analyzed possess pustulan (1-6,beta-D-glucan)which is a major component of fungal and lichen cell walls. Therefore, many animals have antibodies to this polysaccharide in the absence of exposure to A. suis. Thses antibodies may provide naive pigs with some level of protection against the O1 strains [2], [1]
Distribution
Worldwide
References
- ↑ 1.0 1.1 Slavic, D., DeLay, J., Hayes, M.A., MacInnes, J.I.(2000) Comparative pathogenicity of different Actinobacillus suis O/K serotypes. Canadian Journal of Veterinary Research, 64(2):81-87.
- ↑ MacInnes, J.I., Desrosiers, R.(1999) Agents of the "suis-ide diseases" of swine: Actinobacillus suis, Haemophilus parasuis, and Streptococcus suis. Canadian Journal of Veterinary Research, 63(2):83-89; 52 ref.