12株中国艰难梭菌临床分离株的基因分型、毒力和耐药相关基因分子特征研究(英文)

目的初步研究中国艰难梭菌临床分离株的基因分型、毒力和耐药相关基因分子特征。方法采用常规PCR分别检测艰难梭菌A、B毒素的基因tcdA和tcdB、二元毒素(Binary toxin)的cdtA、cdt B基因、和克林霉素耐药相关基因ermB。对其中的产毒艰难梭菌用常规PCR检测16S-23S间隔区多态性,进行基因分型,再用E-test检测对氨比西林(AC)、克林霉素(CM)、甲硝唑(MZ)、万古霉素(VA)的药物敏性。结果12株艰难梭菌中8株为毒素阳性,其中A+B+为5株,A-B+为3株,分别占62.5 %和37.5%;二元毒素均为阴性;耐药基因erm(B)阳性为4株,占50%。8株产毒株中有4个基因型别,以ZRI为主,占62.5%。产毒株对氨比西林、克林霉素、甲硝唑、万古霉素的耐药率分别为37 .5%、87.5 %、12.5 %、0。未发现027型和078型高致病株。结论艰难梭菌产毒株分离率高达66.7 %;中国产毒艰难梭菌临床分离株存在明显的基因多态性,分属于以ZRI为主的4个基因型别;艰难梭菌产毒株对氨比西林、克林霉素、甲硝唑均有一定耐药现象,但对万古霉素敏感。

Primary study on the gene typing, molecular characteristics of virulence and resistance associated gene of 12 Clostridium difficile clinical isolates in China

To investigate the gene typing, molecular characteristics of virulence and resistance associated gene of Clostridiurn difficile from clinical isolates in China, the genes tcdA,tcdB of toxin A and B, cdtA,cdt B of binary-toxin, and erm B of clindamycin resistance were detected by conventional PCR. Genotyping of toxic C. difficile were conducted by means of analysis of 16s-23s internal spacer region polymorphism with PCR assay. Then the antibiotic resistance of toxic C. difficile to ampiciline, clindamycin, metronidazole and vancomycin was conducted with E-test. It was found that 8 toxic C. difficile strains were demonstrated out of 12 clinical isolates, in which 5 strains were tcdA＋ and tcdB＋, and 3 strains tcdA- and tcdB ＋, accounting for 62.5% and 37.5% respectively. Binary-toxin genes detection were negative in all the strains. Clindamycin resistance associated gene ermB was positive in 4 out of 8 toxic C. difficile strains, accounting for 50%. 8 toxic isolates were typed into 4 gene types, the dominant type was ZR I, accounting for 62.5%. Resistance rate of 8 toxic C. difficile strains against ampiciline（AC）, clindamycin（CM）, metronidazole（MZ） and vancomycin（VA） was 37.5% ,87.5%, 12.5%, and 0 respectively. No isolates belonged to ribotype 027 or 078. Isolation rate of toxic C. difficile is high to 66.7%. There is obvious gene polymorphism in clinical isolates of Chinese toxic C. difficite, and ZR I is preponderant genotype in 4 genotypes. C. difficile shows some resistance to ampiciline, clindamycin, metronidazole, but susceptive to vancomycin.