Cloistridioides difficile (CD) represents a major public healthcare-associated infection causing significant morbidity and mortality. The pathogenic effects of CD are mainly caused by the release of two exotoxins into the intestine: toxin A (TcdA) and toxin B (TcdB). CD infection (CDI) can also cause toxemia, explaining the systemic complications of life-threatening cases. Currently, there is a lack of sensitive assays to detect exotoxins circulating in the blood. Here, we report a new semi-quantitative diagnostic method to measure CD toxins serum levels. The dot-blot assay was modified to separately detect TcdA and TcdB in human serum with a limit of detection at the pg/mL levels. TcdA and TcdB concentrations in the plasma of 35 CDI patients were measured at the time of CDI diagnosis and at the fourth and tenth day after CDI diagnosis and initiation of anti-CDI treatment. TcdA and TcdB levels were compared to those determined in nine healthy blood donors. Toxemia was detected in the plasma of 33 out of the 35 CDI cases. We also assessed the relationship between TcdA serum levels and CDI severity, reporting that at the time of CDI diagnosis the proportion of severe CDI cases with a TcdA serum level > 60 pg/µL was higher than in mild CDI cases (29.4% versus 66.6%, p = 0.04). In conclusion, data reported here demonstrate for the first time that toxemia is much more frequent than expected in CDI patients, and specifically that high serum levels of TcdA correlate with disease severity in patients with CDI.

中文翻译：

---

艰难梭菌感染患者的高血清毒素 A 水平与疾病严重程度相关

艰难梭菌(CD) 代表一种主要的公共医疗保健相关感染，导致显着的发病率和死亡率。CD的致病作用主要是由两种外毒素释放到肠道中引起的：毒素A（TcdA）和毒素B（TcdB）。CD 感染 (CDI) 也可引起毒血症，这解释了危及生命的病例的全身并发症。目前，缺乏灵敏的检测方法来检测血液中循环的外毒素。在这里，我们报告了一种新的半定量诊断方法来测量 CD 毒素血清水平。斑点印迹分析被修改为分别检测人血清中的 TcdA 和 TcdB，检测限在 pg/mL 水平。在 CDI 诊断时以及 CDI 诊断和开始抗 CDI 治疗后第 4 天和第 10 天测量了 35 名 CDI 患者血浆中的 TcdA 和 TcdB 浓度。将 TcdA 和 TcdB 水平与九名健康献血者的水平进行比较。在 35 例 CDI 病例中，有 33 例的血浆中检测到毒血症。我们还评估了 TcdA 血清水平与 CDI 严重程度之间的关系，报告称在 CDI 诊断时，TcdA 血清水平 > 60 pg/µL 的严重 CDI 病例比例高于轻度 CDI 病例（29.4% 对 66.6% ,p = 0.04）。总之，这里报告的数据首次表明，CDI 患者的毒血症比预期的要频繁得多，特别是高血清 TcdA 水平与 CDI 患者的疾病严重程度相关。