title: Investigation of toxin gene diversity, molecular epidemiology, and antimicrobial resistance of Clostridium difficile isolated from 12 hospitals in South Korea.
abstract: BACKGROUND
  Clostridium difficile is a major cause of antibiotic-associated diarrhea. The objective of this study was to characterize clinical isolates of C. difficile obtained from various regions in Korea with regard to their toxin status, molecular type, and antimicrobial susceptibility.
  
  
  METHODS
  We analyzed a total of 408 C. difficile isolates obtained between 2006 and 2008 from 408 patients with diarrhea in 12 South Korean teaching hospitals. C. difficile toxin genes tcdA, tcdB, cdtA, and cdtB were detected by PCR. Molecular genotyping was performed by PCR ribotyping. Antimicrobial susceptibilities of the 120 C. difficile isolates were assessed by agar dilution methods.
  
  
  RESULTS
  Among 337 toxigenic isolates, 105 were toxin A-negative and toxin B-positive (A(-)B(+)) and 29 were binary toxin-producing strains. PCR ribotyping showed 50 different ribotype patterns. The 5 most frequently occurring ribotypes comprised 62.0% of all identified ribotypes. No isolate was susceptible to cefoxitin, and all except 1 were susceptible to piperacillin and piperacillin-tazobactam. The resistance rates of isolates to imipenem, cefotetan, moxifloxacin, ampicillin, and clindamycin were 25%, 34%, 42%, 51%, and 60%, respectively. The isolates showed no resistance to metronidazole or vancomycin.
  
  
  CONCLUSIONS
  This is the first nationwide study on the toxin status, including PCR ribotyping and antimicrobial resistance, of C. difficile isolates in Korea. The prevalence of A-B+ strains was 25.7%, much higher than that reported from other countries. Binary toxin-producing strains accounted for 7.1% of all strains, which was not rare in Korea. The most prevalent ribotype was ribotype 017, and all A-B+ strains showed this pattern. We did not isolate strains with decreased susceptibility to metronidazole or vancomycin.
authors.affiliation: Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Heejung
authors.initials: H
authors.lastname: Kim
authors.forename: Seok Hoon
authors.initials: SH
authors.lastname: Jeong
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Roh
authors.forename: Seong Geun
authors.initials: SG
authors.lastname: Hong
authors.forename: Jong Wan
authors.initials: JW
authors.lastname: Kim
authors.forename: Myung-Geun
authors.initials: MG
authors.lastname: Shin
authors.forename: Mi-Na
authors.initials: MN
authors.lastname: Kim
authors.forename: Hee Bong
authors.initials: HB
authors.lastname: Shin
authors.forename: Young
authors.initials: Y
authors.lastname: Uh
authors.forename: Hyukmin
authors.initials: H
authors.lastname: Lee
authors.forename: Kyungwon
authors.initials: K
authors.lastname: Lee
mesh_terms: D016360:Clostridioides difficile / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D003015:Clostridium Infections / Q000382:microbiology; D003967:Diarrhea / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004768:Enterotoxins / Q000235:genetics*; D014644:Genetic Variation; D005838:Genotype; D006785:Hospitals, University; D006801:Humans; D008826:Microbial Sensitivity Tests; D056910:Republic of Korea; D021521:Ribotyping
chemical_list: D004768:Enterotoxins