25株艰难梭菌多位点序列分型

Multilocus sequence typing of 25 Clostridium difficile isolates

目的比较两种对艰难梭菌多位点序列分型(MLST)的方案并探讨不同来源艰难梭菌之间的关系。方法选取来自不同人群的25株艰难梭菌,分别用Lemee方案(aroE,ddl,dutA,tpi,recA,gmk,sodA管家基因)和David方案(adk,atpA,dxr,glyA,recA,soda,tpi管家基因)进行多位点序列分型,用START系统及Bionumerics软件分析这些位点及等位基因谱的特征。结果位点分析结果表明,Lemee方案中有2株菌的ddl位点为无效位点,其余的6个管家基因有3～5个等位基因,等位基因之间有3～11个多态性位点。非同义突变/同义突变(dN/dS)为0.000 0～0.261 1;David方案中的7个管家基因有3～5个等位基因,等位基因之间有2～9个多态性位点。dN/dS为0.000 0～0.280 6。等位基因图谱特征结果表明,Lemee方案出现了13个ST型别(ST1/2/3/6/7/13/31/39/48/A/B/C/D),ST6(5)为优势型别;David方案共出现11个ST型别(ST2/3/15/35/37/54/55/92/99/102/117),其中ST54(6),ST37(5)为优势型别。来源于成人和婴幼儿的菌株并未形成各自特异的序列型。结论对于艰难梭菌多位点序列分型,David的方案更可取,ST与宿主人群的来源没有明显的相关性。

Objective To compare two schemes of multilocus sequence typing for Clostridium difficile and understand the relationship of strains from variant sources.Methods Twenty-five isolates of Clostridium difficile isolates from variant human population were collected.Lemee′s scheme（aroE,ddl,dutA,tpi,recA,gmk,sodA） and David′s scheme（adk,atpA,dxr,glyA,recA,sodA,tpi） were performed respectively.START program and Bionumerics software were used to analyze the selected loci and investigate the characteristics of sequence type.Results Analysis of the loci revealed that ddl was a null locus in 2 isolates by Lemme′s scheme.The other 6 loci displayed 3 to 5 alleles and the number of polymorphic sites of given allele varied from 3 to 11.The ratios of nonsynonymous to synonymous substitutions（dN/dS） varied from 0 to 0.261 1.Seven loci in David′ scheme displayed from 3 to 5 alleles and the number of polymorphic sites varied from 2 to 9.The ratios of dN/dS was 0 to 0.280 6.Thirteen ST types（ST1/2/3/6/7/13/31/39/48/A/B/C/D） were found by Lemme′s profile and ST6（5）was the dominant type of sequence.Eleven STs（ST2/3/15/35/37/54/55/92/99/102/117） were generated by David′s scheme.ST54（6） and ST37（5） were the dominant type of sequence.No specific ST was generated in the strains from children and adults.Conclusion For multilocus sequence typing of Clostridium difficile strains in China,David′s scheme is much more desirable.There was no significant correlation between ST type and specific host population.