Pourbakhsh S A, Boulianne M, Martineau-Doizé B, Dozois C M, Desautels C, Fairbrother J M
Département de Pathologie et Microbiologie, Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada.
Avian Dis. 1997 Jan-Mar;41(1):221-33.
In order to study the dynamics of avian colibacillosis, commercial broiler chickens were inoculated with a pathogenic Escherichia coli strain (01:K1:H7) into the left caudal thoracic air sac. Chickens were euthanatized at different times from 3 to 48 hr postinoculation and examined for bacterial counts and macroscopic and microscopic lesions. The E. coli strain colonized the air sacs, lungs, and trachea and was recovered from blood and all tested extrarespiratory organs of inoculated birds. A gradual increase in bacterial counts in the trachea, lungs, air sacs, and liver was observed from 3 to 12 hr. Clinical signs and macroscopic lesions of colibacillosis were observed in all inoculated birds. Moderate to severe lesions of airsacculitis, pericarditis, perihepatitis, and splenic hypertrophy were observed. Microscopically, inflammatory cell infiltration, serious to fibrinous exudate, and cellular debris on serosal surfaces were present in the liver, spleen, and air sacs. In air sacs, heterophils were present in low numbers perivascularly 3 hr after inoculation and became more numerous by 24 hr postinoculation. Ultrastructurally, epithelial cells in the air sacs and in air capillary regions of the lung were swollen and vacuolated beginning at 3 hr postinoculation. Bacteria were adherent to and present within the epithelial cells at 3 hr postinoculation and were also seen in phagocytic cells and, rarely, in the connective tissue of these organs at 24 hr postinoculation. These results indicate that both air sacs and lungs can be the portal of entry for E. coli into the systemic circulation, probably via damaged epithelium.
为了研究禽大肠杆菌病的发病机制，将商业肉鸡的左尾侧胸气囊接种致病性大肠杆菌菌株（01:K1:H7）。在接种后3至48小时的不同时间对鸡实施安乐死，并检查细菌数量以及肉眼和显微镜下的病变情况。大肠杆菌菌株定殖于气囊、肺和气管，并从接种鸡的血液和所有测试的呼吸外器官中分离出来。在3至12小时内，观察到气管、肺、气囊和肝脏中的细菌数量逐渐增加。在所有接种鸡中均观察到大肠杆菌病的临床症状和肉眼病变。观察到中度至重度的气囊炎、心包炎、肝周炎和脾肿大病变。在显微镜下，肝脏、脾脏和气囊的浆膜表面存在炎性细胞浸润、严重至纤维素性渗出物以及细胞碎片。在气囊中，接种后3小时血管周围存在少量嗜异性粒细胞，接种后24小时数量增多。在超微结构上，接种后3小时开始，气囊和肺的气毛细血管区域的上皮细胞肿胀并出现空泡。接种后3小时细菌附着于上皮细胞并存在于其中，接种后24小时在吞噬细胞中也可见到细菌，在这些器官的结缔组织中很少见。这些结果表明，气囊和肺都可能是大肠杆菌进入体循环的门户，可能是通过受损的上皮细胞。
