Clostridium difficile toxinotypes are groups of strains defined by changes in the PaLoc region encoding two main virulence factors: toxins TcdA and TcdB. Currently, 24 variant toxinotypes (I-XXIV) are known, in addition to toxinotype 0 strains, which contain a PaLoc identical to the reference strain VPI 10463. Variant toxinotypes can also differ from toxinotype 0 strains in their toxin production pattern. The most-studied variant strains are TcdA-, TcdB+ (A-B+) strains and binary toxin CDT-producing strains. Variations in toxin genes are also conserved on the protein level and variant toxins can differ in size, antibody reactivity, pattern of intracellular targets (small GTPases) and consequently in their effects on the cell. Toxinotypes do not correlate with particular forms of disease or patient populations, but some toxinotypes (IIIb and VIII) are currently associated with disease of increased severity and outbreaks worldwide. Variant toxinotypes are very common in animal hosts and can represent from 40% to 100% of all isolates. Among human isolates, variant toxinotypes usually represent up to 10% of strains but their prevalence is increasing.

中文翻译：

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大梭菌毒素的异质性：艰难梭菌毒素型的重要性。

艰难梭菌的毒素型是通过编码两个主要毒力因子：毒素TcdA和TcdB的PaLoc区域变化定义的菌株组。当前，除了含有与参考菌株VPI 10463相同的PaLoc的Paloc 0株以外，还已知24种变异的toxinotypes（I-XXIV）。变异的toxinotypes在毒素产生模式上也可以不同于toxinotype 0菌株。研究最多的变异株是TcdA-，TcdB +（A-B +）株和二元毒素CDT产生株。毒素基因的变异在蛋白质水平上也是保守的，变异毒素的大小，抗体反应性，细胞内靶标（小GTP酶）的模式以及因此对细胞的作用也可能不同。毒素型与特定形式的疾病或患者群体无关，但目前有些毒素型（IIIb和VIII）与全球范围内严重程度增加和疾病爆发的疾病有关。变型毒素型在动物宿主中非常常见，可以代表所有分离株的40％至100％。在人类分离株中，变型毒素型通常占菌株的10％，但其流行率正在上升。