title: Mesenteric lymphangitis and sepsis due to RTX toxin-producing Actinobacillus spp in 2 foals with hypothyroidism-dysmaturity syndrome.
abstract: Actinobacillus suis-like organisms (ASLOs) have been isolated from the genital, respiratory, and digestive tracts of healthy adult horses, horses with respiratory disease, and septic foals. Two foals with congenital hypothyroidism-dysmaturity syndrome from separate farms developed ASLO infection. At necropsy, both had contracted carpal flexor tendons, thyroid hyperplasia, and thrombotic and necrotizing mesenteric lymphangitis and lymphadenitis; one foal also had mandibular prognathism. Numerous ASLOs were isolated from tissues from both foals, including intestine. Biochemical testing and mass spectrometric analysis of the two Actinobacillus isolates did not allow unequivocal identification. Comparative genetic analysis was done on these and similar isolates, including phylogeny based on 16S rRNA, rpoB and recN genes, as well as RTX (repeat in toxin) toxin typing of apxIA-apxIVA and aqxA genes. One isolate was identified as Actinobacillus               suis sensu stricto, based on the presence of apxIA and apxIIA but not aqxA, whereas the other isolate had aqxA but neither apxIA nor apxIIA, consistent with A equuli ssp haemolyticus. Based on genotypic analysis of the isolates included for comparison, 3 of 3 equine ASLOs and 2 of 5 A equuli isolates were reclassified as A equuli subsp haemolyticus, emphasizing the importance of toxin genotyping in accurate classification of actinobacilli.
authors: Veterinary Diagnostic Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97339-0429, USA. christiane.loehr@oregonstate.edu
authors: C V
authors: CV
authors: Löhr
authors: U
authors: U
authors: Polster
authors: P
authors: P
authors: Kuhnert
authors: A
authors: A
authors: Karger
authors: F R
authors: FR
authors: Rurangirwa
authors: J P
authors: JP
authors: Teifke
mesh_terms: D000188:Actinobacillus / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D000189:Actinobacillus Infections / Q000662:veterinary*; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005838:Genotype; D006734:Horse Diseases / Q000382:microbiology*; D006736:Horses; D007037:Hypothyroidism / Q000150:complications / Q000382:microbiology / Q000662:veterinary*; D008205:Lymphangitis / Q000382:microbiology / Q000473:pathology / Q000662:veterinary; D008297:Male; D008640:Mesenteric Lymphadenitis / Q000382:microbiology / Q000473:pathology / Q000662:veterinary; D010802:Phylogeny; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: C079721:ApxIII toxin protein, Actinobacillus; D001426:Bacterial Proteins