title: Effect of antibiotic sub inhibitory concentration on cytolethal distending toxin production by Campylobacter jejuni.
abstract: OBJECTIVE
  To investigate the effect of pre-exposure antibiotics on cytolethal distending toxin (CDT) production and toxigenic effect of C. jejuni.
  
  
  METHODS
  Sonicates and filtrates were prepared from known cdt+ and cdt- isolates of C. jejuni which had been pre-exposed to varying concentrations (MIC, 1/2 MIC, 1/4 MIC, 1/8 MIC) of erythromycin and ciprofloxacin. The CDT toxigenic effect was examined using INT 407 and HeLa cells.
  
  
  RESULTS
  A trend of increased toxigenic effect was observed with pre-exposure to antibiotics. This was more pronounced with erythromycin pre-exposure compared to ciprofloxacin. Although a trend of increasing toxigenic effect with decreasing antibiotic concentration was demonstrable, some differences were observed between isolates. In one isolate the increased toxigenic effect was statistically significant (P<0.05) at 1/4 MIC in INT 407 cells and at 1/8 MIC in HeLa cells.
  
  
  CONCLUSIONS
  This study provides evidence of an association between CDT production by C. jejuni and pre-exposure to antibiotics. Pre-exposure to ciprofloxacin and erythromycin at concentrations below MICs could potentiate CDT activity. Further work is needed to elucidate the mechanism involved. We recommend that these antibiotics be used in the treatment of C. jejuni enteritis only when strongly indicated and with careful monitoring of patients.
authors.affiliation: Department of Microbiology, Immunology and Infectious Diseases, Arabian Gulf University, P.O. Box 26671, Manama, Kingdom of Bahrain. ismaeel@agu.edu.bh
authors.forename: Abdulrahman Y
authors.initials: AY
authors.lastname: Ismaeel
authors.forename: Abiola C
authors.initials: AC
authors.lastname: Senok
authors.forename: Khalid M
authors.initials: KM
authors.lastname: Bindayna
authors.forename: Moiz
authors.initials: M
authors.lastname: Bakhiet
authors.forename: Ali
authors.initials: A
authors.lastname: Al Mahmeed
authors.forename: Ahmed Q
authors.initials: AQ
authors.lastname: Yousif
authors.forename: Giuseppe A
authors.initials: GA
authors.lastname: Botta
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D019072:Antibiotic Prophylaxis; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics; D002169:Campylobacter Infections / Q000382:microbiology; D016123:Campylobacter jejuni / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D002460:Cell Line; D002939:Ciprofloxacin / Q000494:pharmacology; D004269:DNA, Bacterial / Q000302:isolation & purification; D003967:Diarrhea / Q000382:microbiology; D004917:Erythromycin / Q000494:pharmacology; D005243:Feces / Q000382:microbiology; D005838:Genotype; D006367:HeLa Cells; D006801:Humans; D008826:Microbial Sensitivity Tests
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D004269:DNA, Bacterial; C067044:cytolethal distending toxin; D002939:Ciprofloxacin; D004917:Erythromycin