We have sequenced, assembled and annotated the genome of Clostridium sordellii strain UMC2. Paraclostridium sordellii strain:UMC2

Clostridium sordellii is an anaerobic bacterium associated with rare but severe infections of man and animals. Human infections are associated with trauma, toxic shock and often-fatal gynaecological infections. Some strains are known to produce the large clostridial cytotoxins TcsH and TcsL, relatives of the cytotoxins found in C. difficile, C. novyi and C. perfringens. These 4 strains are part of a larger collection that reveal a diverse phylogenetic distribution. Although all strains originated from animal or clinical disease, only 5 strains contained cytotoxin genes: 4 strains contain tcsL alone and one strain contains tcsL and tcsH. Where present, tcsL and tcsH were localised on a pathogenicity locus, distinct to that present in C. difficile. In contrast to C. difficile, the C. sordellii tcsL and tcsH genes were always localised on plasmids, designated pCS1-1 in strain ATCC9714 and pCS1-3 in strain JGS6382. Phylogenetic analysis suggests gain and loss of entire toxigenic plasmids in addition to horizontal transfer of the pathogenicity locus. A high quality, annotated draft sequence of ATCC9714 reveals many putative virulence factors including genes for neuraminidase, phospholipase C and a cholesterol-dependent cytolysin sordellilysin that are highly conserved between all strains sequenced here. Our finding suggest that the cytotoxins may not be the primary virulence factors in the majority of infections, but that acquisition of these toxins mayprecipitate severe infection.

索氏梭菌（Clostridium sordellii）是一种厌氧菌（anaerobic bacterium），与人类和动物的罕见但重症感染密切相关。人类感染常与创伤、中毒性休克以及常可致死的妇科感染有关。部分菌株可产生大型梭菌毒素（large clostridial cytotoxins）TcsH与TcsL，这类毒素与艰难梭菌（C. difficile）、诺维氏梭菌（C. novyi）以及产气荚膜梭菌（C. perfringens）中的毒素具有亲缘关系。上述4株菌株隶属于更大的菌株集合，该集合展现出多样化的系统发育分布特征。尽管所有菌株均分离自动物或临床病例，但仅5株菌株携带毒素基因：其中4株仅携带tcsL基因，1株同时携带tcsL与tcsH基因。当携带上述毒素基因时，tcsL与tcsH均定位于一个致病岛（pathogenicity locus），该致病岛与艰难梭菌中的致病岛存在显著差异。与艰难梭菌不同，索氏梭菌的tcsL和tcsH基因始终定位于质粒上：ATCC9714菌株中的质粒命名为pCS1-1，JGS6382菌株中的质粒命名为pCS1-3。系统发育分析表明，除致病岛的水平转移外，产毒质粒的整体获取与丢失也是其演化过程中的重要事件。对ATCC9714菌株的高质量注释草图基因组序列分析显示，其携带多种潜在毒力因子，包括神经氨酸酶、磷脂酶C基因，以及一种胆固醇依赖性溶细胞素——索氏溶素（sordellilysin），该溶素在本次测序的所有菌株中均高度保守。我们的研究结果表明，在大多数感染病例中，这类梭菌毒素或许并非主要的毒力因子，但获取此类毒素可能会诱发重症感染。