Rönnberg B, Wadström T
J Clin Microbiol. 1983 Jun;17(6):1021-5. doi: 10.1128/jcm.17.6.1021-1025.1983.
Colonies of Escherichia coli from blood agar plates were suspended and lysed in saline containing polymyxin B and a detergent (Triton X-100). The lysates were assayed for heat-labile enterotoxin (LT) by a coagglutination test (coa-test). The coa-test reagent consisted of Formalin-treated and heat-killed cells of Staphylococcus aureus, strain Cowan 1, sensitized with a high-titer rabbit anti-LT serum. Purified LT was detected in the coa-test at the nanogram level (2 to 5 ng), whereas larger amounts of cholera toxin (50 ng) were required to give a positive test. The coa-test was compared with the CHO cell test for detection of LT among E. coli strains isolated from human and animal stool cultures. The results of the coa-test and the CHO cell test correlated with 63 of 67 strains of human origin. Six of nine animal strains, defined as LT positive by the CHO cell test, gave positive results in the coa-test. We conclude that the coa-test is probably accurate and sensitive enough to be used in routine diagnosis of LT-producing E. coli strains isolated from human stool cultures. No special laboratory equipment is required, which makes the coa-test suited for diagnosis of enterotoxigenic E. coli in small hospital laboratories and in developing countries.
将血琼脂平板上的大肠杆菌菌落悬浮于含有多粘菌素B和去污剂（曲拉通X-100）的盐溶液中并进行裂解。通过协同凝集试验（coa试验）检测裂解物中的不耐热肠毒素（LT）。coa试验试剂由经福尔马林处理并热灭活的金黄色葡萄球菌考恩1菌株细胞组成，用高滴度兔抗LT血清致敏。在coa试验中可检测到纳克水平（2至5纳克）的纯化LT，而霍乱毒素（50纳克）需要更多量才能给出阳性试验结果。将coa试验与用于检测从人和动物粪便培养物中分离的大肠杆菌菌株中LT的CHO细胞试验进行比较。coa试验和CHO细胞试验的结果与67株人源菌株中的63株相关。CHO细胞试验定义为LT阳性的9株动物菌株中有6株在coa试验中给出阳性结果。我们得出结论，coa试验可能足够准确和灵敏，可用于从人粪便培养物中分离的产LT大肠杆菌菌株的常规诊断。不需要特殊的实验室设备，这使得coa试验适用于小型医院实验室和发展中国家对产肠毒素大肠杆菌的诊断。
