title: Prevalence and antimicrobial resistance of Campylobacter in antimicrobial-free and conventional pig production systems.
abstract: The objectives of this study were to determine and compare the prevalence and antimicrobial resistance of Campylobacter species in swine reared in conventional and antimicrobial-free (ABF) production systems. Campylobacter coli was the predominant species, with 1,459 isolates (99%) in the study. We found significantly higher prevalence of C. coli on the ABF farms (77.3%) than on the conventional farms (27.6%) among pigs at the nursery stage (P < 0.001). At slaughter, we found significantly higher prevalence at the postevisceration than at the preevisceration stage (P < 0.001) in both production systems. The 1,459 C. coli isolates were tested with the agar dilution method for their susceptibility to six antimicrobials: chloramphenicol, ciprofloxacin, erythromycin, gentamicin, nalidixic acid, and tetracycline. Resistance was most prevalent against tetracycline (66.2% of isolates) followed by erythromycin (53.6% of isolates). Frequency of resistance to these two antimicrobials was significantly higher among conventional herds (83.4% for tetracycline and 77% for erythromycin) than among ABF herds (56.2% for tetracycline and 34.5% for erythromycin). Resistance to ciprofloxacin at the MIC (> 4 mg/liter) was also found on farms in both systems. Multidrug-resistant C. coli strains were detected in both the conventional (7%) and ABF (4%) herds. This is the first report of ciprofloxacin-resistant strains of C. coli in ABF pigs in the United States. These findings highlight the high prevalence of antimicrobial-resistant C. coli in both conventional and ABF pig production systems and have significant implications for the persistence of antimicrobial-resistant Campylobacter in the pig production environment regardless of levels of antimicrobial use.
authors.affiliation: Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina 27606, USA.
authors.forename: Siddhartha
authors.initials: S
authors.lastname: Thakur
authors.forename: Wondwossen A
authors.initials: WA
authors.lastname: Gebreyes
mesh_terms: D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002167:Campylobacter / Q000187:drug effects* / Q000302:isolation & purification*; D017000:Campylobacter coli / Q000187:drug effects / Q000302:isolation & purification; D015169:Colony Count, Microbial / Q000662:veterinary; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D005525:Food-Processing Industry / Q000592:standards*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D015995:Prevalence; D013552:Swine; D014481:United States / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents