title: A seventeen-year observation of the antimicrobial susceptibility of clinical Campylobacter jejuni and the molecular mechanisms of erythromycin-resistant isolates in Beijing, China.
abstract: OBJECTIVE
  To investigate the dynamic development of the antimicrobial resistance of Campylobacter jejuni isolated from human diarrhea in Beijing, China, between 1994 and 2010, and to further analyze the molecular mechanisms of erythromycin-resistant strains.
  
  
  METHODS
  Susceptibility tests were performed on 203 non-duplicate clinical C. jejuni strains against eight common antibiotics using the standard agar dilution method. The molecular determinants were further studied in the erythromycin (ERY) non-susceptible strains. The analysis focused on the 23S rRNA gene, the rplD and rplV ribosomal genes, the ermB gene, and the regulatory region of the CmeABC efflux pump.
  
  
  RESULTS
  The rates of resistance of C. jejuni to ciprofloxacin (CIP), nalidixic acid (NAL), doxycycline (DOX), tetracycline (TET), florfenicol (FFC), and chloramphenicol (CHL) increased significantly over the period studied (all p<0.05). Similarly, the proportions of resistant patterns (CIP-NAL-DOX-TET, CIP-NAL-DOX-TET-FFC, and CIP-NAL-DOX-TET-CHL) increased remarkably. In this study, 4.4% (9/203) of C. jejuni strains were ERY non-susceptible. The A2075G mutation in the 23S rRNA was found in all of the resistant strains except cj8091, which harbored the ermB gene. Interestingly, the ermB gene was also detected in intermediately resistant isolates, and the earliest ermB-positive strain cj94473 was derived in 1994. Moreover, none of the ribosomal rplD or rplV genes harbored mutations that have been described to confer resistance to macrolides. Different mutations affecting the regulatory region of the CmeABC efflux pump were also found.
  
  
  CONCLUSIONS
  This is the first comprehensive study on the recent trend in antimicrobial resistance and the molecular mechanisms of macrolide resistance in clinical C. jejuni strains isolated in China. More stringent monitoring and regulation of human and animal antimicrobial use are warranted.
authors.affiliation: Department of Infectious Diseases and the Center for Liver Diseases, Peking University First Hospital, Beijing, 100034, China.
authors.forename: Jiyuan
authors.initials: J
authors.lastname: Zhou
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, 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.forename: Maojun
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Infectious Diseases and the Center for Liver Diseases, Peking University First Hospital, Beijing, 100034, China.
authors.forename: Wanna
authors.initials: W
authors.lastname: Yang
authors.affiliation: Department of Infectious Diseases and the Center for Liver Diseases, Peking University First Hospital, Beijing, 100034, China.
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Department of Infectious Diseases and the Center for Liver Diseases, Peking University First Hospital, Beijing, 100034, China. Electronic address: john131212@sina.com.
authors.forename: Guiqiang
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Infectious Diseases and the Center for Liver Diseases, Peking University First Hospital, Beijing, 100034, China. Electronic address: houfqys@139.com.
authors.forename: Fengqin
authors.initials: F
authors.lastname: Hou
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016123:Campylobacter jejuni / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004917:Erythromycin / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests
chemical_list: D000900:Anti-Bacterial Agents; D004917:Erythromycin
keywords: Campylobacter jejuni; Erythromycin; Molecular mechanism; Resistance