Veterinary Diagnostic Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97339-0429, USA.
Vet Pathol. 2012 Jul;49(4):592-601. doi: 10.1177/0300985811402844. Epub 2011 Apr 1.
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.
从健康成年马的生殖道、呼吸道和消化道，以及患有呼吸道疾病和败血症的马驹中分离到猪源类放线杆菌（Actinobacillus suis-like organisms，ASLO）。来自两个不同农场的患有先天性甲状腺功能减退-发育不良综合征的两匹驹出现了 ASLO 感染。在尸检时，两匹马都患有腕屈肌腱挛缩、甲状腺增生、血栓性和坏死性肠系膜淋巴结炎和淋巴结炎；一匹驹还患有下颌前突。从两匹马驹的组织中分离到大量的 ASLO，包括肠道。对这两株和类似的放线杆菌分离株进行了生化和质谱分析，但不能明确鉴定。对这些分离株和类似的分离株进行了比较遗传分析，包括基于 16S rRNA、rpoB 和 recN 基因的系统发育，以及 apxIA-apxIVA 和 aqxA 基因的 RTX（毒素重复）毒素分型。一株分离株被鉴定为猪源类放线杆菌，因为存在 apxIA 和 apxIIA 但不存在 aqxA，而另一株分离株存在 aqxA 但不存在 apxIA 或 apxIIA，与 A equuli ssp haemolyticus 一致。根据包括比较在内的分离株的基因型分析，3 匹马源 ASLO 和 5 株 A equuli 分离株中的 2 株被重新分类为 A equuli subsp haemolyticus，这强调了毒素基因分型在准确分类放线杆菌中的重要性。
