Prevalence and antimicrobial resistance of Campylobacter in antimicrobial-free and conventional pig production systems.
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.
Thakur
Siddhartha
S
Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina 27606, USA.
Gebreyes
Wondwossen A
WA
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
D000900:Anti-Bacterial Agents