Arroyo Luis G, Weese J Scott, Staempfli Henry R
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
J Vet Intern Med. 2004 Sep-Oct;18(5):734-8. doi: 10.1892/0891-6640(2004)18<734:ecdeif>2.0.co;2.
Despite empirical clinical association of infection with Clostridium difficile with colitis in horses, a causal link has not been confirmed. The objective of this study was to develop a model of C. difficile-associated diarrhea in foals with normal transfer of passive immunity. Nine 1-day-old pony foals were inoculated intragastrically with spores or vegetative cells of C. difficile. Five foals were challenged with spores, with 2 receiving 10(5) colony-forming units (CFUs) and concurrently 3 receiving 10(7) CFUs once daily for 3 days. Clindamycin was administered orally to disrupt gastrointestinal flora. A further 4 foals were challenged by orogastric administration of 10(10) CFUs of vegetative cells once daily for 3 days or until diarrhea developed. This group did not receive clindamycin. Spore and vegetative cell preparations were negative for toxins of C. difficile and common enteropathogens. Clinical signs varied from mild abdominal discomfort and pasty feces to colic and watery diarrhea in 8 of 9 foals. Four of 5 foals challenged with spores developed mild diarrhea, whereas all foals challenged with vegetative cells developed moderate to severe diarrhea. C. difficile was isolated from feces of all foals between 24 and 72 hours after inoculation and toxins A or B or both were detected in the feces of all foals by an enzyme-linked immunosorbent assay. We concluded that spores and vegetative cells of C. difficile are capable of colonizing the gastrointestinal tract, producing toxins, and inducing clinical signs similar to those encountered in naturally occurring cases. This study fulfilled Koch's postulates for C. difficile-associated diarrhea in foals and provides a model for consistent reproduction of the disease for future studies.
尽管在马匹中，艰难梭菌感染与结肠炎存在临床经验关联，但因果关系尚未得到证实。本研究的目的是建立一个在被动免疫正常转移的新生马驹中艰难梭菌相关性腹泻的模型。9匹1日龄小马驹经胃内接种艰难梭菌的孢子或营养细胞。5匹小马驹用孢子进行攻击，其中2匹接受10⁵菌落形成单位（CFU），另外3匹同时每天接受1次10⁷CFU，持续3天。口服克林霉素以破坏胃肠道菌群。另外4匹小马驹通过经口胃管给药，每天1次，每次10¹⁰CFU营养细胞，持续3天或直至出现腹泻。该组未接受克林霉素。孢子和营养细胞制剂对艰难梭菌毒素和常见肠道病原体呈阴性。临床症状从轻度腹部不适和糊状粪便到9匹小马驹中的8匹出现绞痛和水样腹泻不等。5匹用孢子攻击的小马驹中有4匹出现轻度腹泻，而所有用营养细胞攻击的小马驹都出现中度至重度腹泻。在接种后24至72小时内，从所有小马驹的粪便中分离出艰难梭菌，并且通过酶联免疫吸附测定在所有小马驹的粪便中检测到毒素A或B或两者。我们得出结论，艰难梭菌的孢子和营养细胞能够在胃肠道定植、产生毒素并诱发与自然发生病例中相似的临床症状。本研究满足了小马驹艰难梭菌相关性腹泻的科赫法则，并为未来研究提供了一种可重复该疾病的模型。
