title: Sequence variation in tcdA and tcdB of Clostridium difficile: ST37 with truncated tcdA is a potential epidemic strain in China.
abstract: Clostridium difficile is a well-known nosocomial infectious pathogen. Research on C. difficile infection has primarily focused on strains such as the hypervirulent PCR ribotype 027 (sequence type 1 [ST1]) emerging in Europe and North America. However, other new emerging ribotypes in some countries have attracted attention, such as PCR ribotype 17 (ST37) in Asia and Latin America. We collected 70 strains and sequenced their toxin genes, tcdA and tcdB. Multilocus sequence typing (MLST) was used to study their population structure. In addition, tcdA and/or tcdB sequences of 25 other isolates were obtained from GenBank. Single nucleotide polymorphisms (SNPs) were identified and analyzed. Phylogenetic analyses were performed to study toxin gene evolution. All tcdA and tcdB sequences were divided into 1 of 16 types (denoted A01 to -16 and B01 to -16, respectively). Hypervirulent strain RT027 is A13B12, and RT078 is A14B10, whereas the newly epidemic strain RT017 is A15B13. SNP analysis suggests the possibility of recombination in tcdB, perhaps through horizontal gene transfer. SNPs were also found in the sequences corresponding to the PCR primers widely used for toxin detection. Our study shows that ST037 shares a few genotypic features in its tcdA and tcdB genes with some known hypervirulent strains, indicating that they fall into a unique clade. Our findings can be used to map the relationships among C. difficile strains more finely than can be done with less sensitive methods, such as toxinotyping or even MLST, to reveal their inherent epidemiological characteristics.
authors: State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.
authors: Pengcheng
authors: P
authors: Du
authors: State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
authors: Bo
authors: B
authors: Cao
authors: State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
authors: Jing
authors: J
authors: Wang
authors: State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.
authors: Wenge
authors: W
authors: Li
authors: Department of Clinical Laboratory, China-Japan Friendship Hospital, Beijing, China.
authors: Hongbing
authors: H
authors: Jia
authors: State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.
authors: Wen
authors: W
authors: Zhang
authors: State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.
authors: Jinxing
authors: J
authors: Lu
authors: Key Laboratory of Surveillance and Early Warning on Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China.
authors: Zhongjie
authors: Z
authors: Li
authors: Key Laboratory of Surveillance and Early Warning on Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China.
authors: Hongjie
authors: H
authors: Yu
authors: State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China chenchen@icdc.cn chengying@chinacdc.cn.
authors: Chen
authors: C
authors: Chen
authors: Key Laboratory of Surveillance and Early Warning on Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China chenchen@icdc.cn chengying@chinacdc.cn.
authors: Ying
authors: Y
authors: Cheng
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics*; D002681:China / Q000453:epidemiology; D016360:Clostridioides difficile / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D003015:Clostridium Infections / Q000453:epidemiology / Q000382:microbiology*; D016000:Cluster Analysis; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology*; D004768:Enterotoxins / Q000235:genetics*; D058872:Epidemics; D005838:Genotype; D006801:Humans; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D017385:Sequence Homology
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004269:DNA, Bacterial; D004768:Enterotoxins; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile