Berkhoff H A, Vinal A C
Avian Dis. 1986 Jan-Mar;30(1):117-21.
In the course of our molecular studies of virulence factors associated with invasive avian Escherichia coli infections, it was first necessary to distinguish between common E. coli and those that cause septicemia in poultry. We found a direct correlation between the ability of clinical isolates of E. coli to bind Congo red dye (CR) and their ability to cause septicemic infection in chickens. This finding was supported by bacteriological studies of 30 broiler flocks (26 sick and 4 healthy) and by virulence studies in chickens and mice. All 144 isolates of E. coli from internal tissues of diseased birds were determined to be CR-positive (red colonies). Congo-red-positive E. coli colonies were isolated from air sacs, pericardium, liver, lung, joint fluid, and heart blood of chickens with lesions of colisepticemia. In contrast, of 170 E. coli isolates from the poultry house environment and from the trachea and cloaca of healthy birds, more than half were CR-negative (white colonies). No CR-negative (white) E. coli colonies were found in internal organs from birds with typical lesions of colisepticemia. We feel that these preliminary findings suggest that the CR dye binding could be used as a phenotypic marker to distinguish between invasive and noninvasive isolates.
在我们对与侵袭性禽源大肠杆菌感染相关的毒力因子进行分子研究的过程中，首先有必要区分普通大肠杆菌和那些在家禽中引起败血症的大肠杆菌。我们发现大肠杆菌临床分离株结合刚果红染料（CR）的能力与其在鸡中引起败血性感染的能力之间存在直接关联。这一发现得到了对30个肉鸡群（26个患病群和4个健康群）的细菌学研究以及在鸡和小鼠中的毒力研究的支持。从患病鸟类内部组织分离出的所有144株大肠杆菌均被确定为CR阳性（红色菌落）。从患有大肠杆菌败血症病变的鸡的气囊、心包、肝脏、肺、关节液和心血中分离出刚果红阳性大肠杆菌菌落。相比之下，从禽舍环境以及健康鸟类的气管和泄殖腔中分离出的170株大肠杆菌中，超过一半是CR阴性（白色菌落）。在患有典型大肠杆菌败血症病变的鸟类的内脏器官中未发现CR阴性（白色）大肠杆菌菌落。我们认为这些初步发现表明，CR染料结合可作为区分侵袭性和非侵袭性分离株的表型标记。
