title: Comparative pathogenicity of different Actinobacillus suis O/K serotypes.
abstract: The pathogenicity of Actinobacillus suis serotypes O1/K1 (strain SO4), O1/K2 (strain C84), and O2/K2 (strain H91-0380) was evaluated in specific-pathogen-free (SPF) piglets challenged by intraperitoneal inoculation with approximately 1 x 10(7) colony-forming units per mL. All 3 strains produced peritonitis, but differences were observed in the composite histopathologic scores (P = 0.001) and in their ability to spread (P = 0.008) at 7 h post challenge. The O2/K2 strain caused the most severe peritonitis and disseminated most widely to other tissues. Moderate lesions were seen with the O1/K2 strain while the O1/K1 strain caused mild lesions and remained largely localized to the peritoneum. In an attempt to explain the basis of observed differences, the serum sensitivity of 9 A. suis strains with different O and K types was assessed. Regardless of the O/K type, all of the isolates tested were serum resistant. Moreover, most A. suis isolates grew as well or better in complement-replete sera as they did in complement-depleted sera. These observations indicate that although 02 and K2 strains had a greater propensity to cause a disseminating septic inflammatory response in pigs, they were no more resistant to complement-mediated killing than O1 strains.
authors.affiliation: Department of Pathobiology, University of Guelph, Ontario.
authors.forename: D
authors.initials: D
authors.lastname: Slavić
authors.forename: J
authors.initials: J
authors.lastname: DeLay
authors.forename: M A
authors.initials: MA
authors.lastname: Hayes
authors.forename: J I
authors.initials: JI
authors.lastname: MacInnes
mesh_terms: D000188:Actinobacillus / Q000472:pathogenicity*; D000189:Actinobacillus Infections / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D008297:Male; D010537:Peritoneum / Q000473:pathology; D018805:Sepsis / Q000209:etiology / Q000382:microbiology / Q000662:veterinary*; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology* / Q000473:pathology