title: Campylobacter susceptibility to ciprofloxacin and corresponding fluoroquinolone concentrations within the gastrointestinal tracts of chickens.
abstract: OBJECTIVE
  This study evaluated the relationship between Campylobacter susceptibility and enteric fluoroquinolone concentrations in chickens treated with different doses of enrofloxacin.
  
  
  RESULTS
  All chickens were challenged with seven fluoroquinolone sensitive Campylobacter jejuni (6.6 x 10(6) CFU per bird) at 2 weeks posthatch. At 26 days of age chickens were treated with 0 (n = 29 birds), 25 mg ml(-1) enrofloxacin (Baytril, Bayer Corp., Shawnee Mission, KS, USA) for 3 days (n = 45 birds) or 50 mg ml(-1) enrofloxacin for 7 days (n = 65 birds) in the drinking water. The crop, upper ileum, lower ileum, ceca and colon contents were collected from both enrofloxacin treatment groups (n = 5 birds per day per treatment group) and nonmedicated controls. The minimum inhibitory concentration (MIC) of ciprofloxacin for Campylobacter increased for isolates from both treatment groups within the first day of dosing and the daily average ranged from 1.4 to 6.5 microg ml(-1) throughout the study. Although enteric fluoroquinolone concentrations were higher (P < 0.05) in birds dosed with 50 mg ml(-1)vs 25 mg ml(-1) enrofloxacin, there were no differences between the isolates collected from these groups for MIC values.
  
  
  CONCLUSIONS
  These data indicate, for the doses used, differences in gut fluoroquinolone concentrations do not produce isolates of Campylobacter with differing susceptibility to ciprofloxacin.
  
  
  CONCLUSIONS
  Using the manufacturers lowest, shortest duration dose vs the highest, longest duration dose of enrofloxacin did not change Campylobacter susceptibility to ciprofloxacin. However, ciprofloxacin MIC values for Campylobacter determined in this study were lower than previously reported.
authors.affiliation: Poultry Production and Product Safety Research Unit, Agricultural Research Service, USDA, Fayetteville, AR 72701, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Farnell
authors.forename: A M
authors.initials: AM
authors.lastname: Donoghue
authors.forename: K
authors.initials: K
authors.lastname: Cole
authors.forename: I
authors.initials: I
authors.lastname: Reyes-Herrera
authors.forename: P J
authors.initials: PJ
authors.lastname: Blore
authors.forename: D J
authors.initials: DJ
authors.lastname: Donoghue
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*; D016123:Campylobacter jejuni / Q000187:drug effects*; D002645:Chickens; D002939:Ciprofloxacin / Q000032:analysis / Q000494:pharmacology; D004326:Drinking; D004334:Drug Administration Schedule; D024881:Drug Resistance, Bacterial; D000077422:Enrofloxacin; D024841:Fluoroquinolones / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*; D005516:Food Microbiology; D041981:Gastrointestinal Tract / Q000737:chemistry / Q000382:microbiology*; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D014867:Water
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D014867:Water; D000077422:Enrofloxacin; D002939:Ciprofloxacin