Resistance to antimicrobial agents of Campylobacter spp. strains isolated from animals in Poland

A total of 69 Campylobacter jejuni and 16 Campylobacter coli strains isolated from chicken, dog and pig stool samples were characterized based on their resistance to five antimicrobial agents and on plasmid pTet profiles. Antimicrobials used in this study were: amoxicillin/clavulanic acid, ciprofloxacin, erythromycin, tetracycline and trimethoprim/sulfamethoxazole. Among the isolates studied, 91.7% were resistant to one or more antimicrobial agent. The highest level of resistance for the whole test group was to trimethoprim/sulfamethoxazole (57.6%), followed by ciprofloxacin (44.2%) and tetracycline (20%). All isolates were susceptible to amoxicillin/clavulanic acid. Strains isolated from chickens were susceptible to erythromycin. Few erythromycin-resistant strains were isolated from dogs and pigs (5.8%). C. coli strains exhibited a higher antibiotic resistance than C. jejuni strains, excluding resistance to trimethoprim/sulfamethoxazole. The pTet plasmid harboring the tet(O) gene was detected in 14 Campylobacter spp. strains. Our studies demonstrate that the majority (71.4%) of tetracycline-resistant isolates carry a plasmid-borne tet(O) gene, particularly strains for which the minimum inhibitory concentration (MIC) are > or = 256 microg/ml. In conclusion, we have found high-level trimethoprim/sulfamethoxazole, ciprofloxacin and tetracycline resistance in Polish strains isolated from different sources. This study has demonstrated that resistance of Campylobacter species differs depending on both the bacterial species and animal origins. All strains that displayed resistance to four antimicrobial agents were isolated from pigs. Localization of the tet(O) gene on either plasmid or chromosome was not found to be correlated with tetracycline resistance.