Abstract：
OBJECTIVE: Diphtheria, still present in many countries of the world, is caused by toxigenic strains of species of the Corynebacterium diphtheriae complex, mainly Corynebacterium diphtheriae and the emerging zoonotic pathogen C. ulcerans. The immunoprecipitation test according to Elek is the gold standard for detection of the major virulence factor diphtheria toxin (DT) in toxigenic corynebacteria. Due to its sophisticated methodological requirements, the classical Elek test is performed mainly by specialized reference laboratories. It was revealed that the current modification of the Elek test does not detect the toxin in weakly toxigenic isolates. Therefore, a more robust method for detecting free DT is urgently needed, especially for toxigenic C. ulcerans strains which are known to produce often much lower amounts of DT than C. diphtheriae.
METHODS: Thirty-one tox-positive C. ulcerans isolates with a negative standard Elek test result previously determined as NTTB (non-toxigenic tox bearing) were re-analyzed in this study using a modified immunoprecipitation method optimized regarding different parameters including type and concentration of antitoxin, medium volume, inoculum distance from the antitoxin disk and position of controls.
RESULTS: All 31 C. ulcerans strains tested positive in the optimized Elek test.
CONCLUSIONS: Only with a reliable and easy-to-handle method for detecting the toxigenicity of C. ulcerans, it is possible to assess the etiological role of this emerging zoonotic bacterium in human pathology.
METHODS: Thirty-one tox-positive C. ulcerans isolates with a negative standard Elek test result previously determined as NTTB (non-toxigenic tox bearing) were re-analyzed in this study using a modified immunoprecipitation method optimized regarding different parameters including type and concentration of antitoxin, medium volume, inoculum distance from the antitoxin disk and position of controls.
RESULTS: All 31 C. ulcerans strains tested positive in the optimized Elek test.
CONCLUSIONS: Only with a reliable and easy-to-handle method for detecting the toxigenicity of C. ulcerans, it is possible to assess the etiological role of this emerging zoonotic bacterium in human pathology.
摘要：
目标：白喉，仍然存在于世界上许多国家，是由白喉棒状杆菌复合体的产毒菌株引起的，主要是白喉棒杆菌和新兴的人畜共患病原体C.ulcerans。根据Elek的免疫沉淀试验是检测产毒棒杆菌中主要毒力因子白喉毒素(DT)的金标准。由于其复杂的方法要求，经典的Elek测试主要由专门的参考实验室进行。据透露，当前对Elek测试的修改未检测到弱产毒分离物中的毒素。因此,迫切需要一种更稳健的检测自由数字孪生的方法，特别是对于已知产生的DT量通常比白喉梭菌低得多的产毒C.ulcerans菌株。
方法：在本研究中，使用针对不同参数（包括抗毒素的类型和浓度）进行了优化的改良免疫沉淀方法，重新分析了31个毒性阳性的溃疡C.中等体积,接种物与抗毒素盘的距离和对照的位置。
结果:在优化的Elek检验中,所有31个C.溃疡菌株测试为阳性。
结论：只有使用可靠且易于操作的方法检测溃疡梭菌的毒性，有可能评估这种新兴的人畜共患细菌在人类病理学中的病因学作用。
方法：在本研究中，使用针对不同参数（包括抗毒素的类型和浓度）进行了优化的改良免疫沉淀方法，重新分析了31个毒性阳性的溃疡C.中等体积,接种物与抗毒素盘的距离和对照的位置。
结果:在优化的Elek检验中,所有31个C.溃疡菌株测试为阳性。
结论：只有使用可靠且易于操作的方法检测溃疡梭菌的毒性，有可能评估这种新兴的人畜共患细菌在人类病理学中的病因学作用。
