Antimicrobial resistance in Enterobacteriaceae strains isolated from organic chicken, conventional chicken and conventional turkey meat: A comparative survey

Mean counts of Enterobacteriaceae were determined for 30 samples each of organic chicken meat, conventional chicken meat and conventional turkey meat to assess differences in contamination. Two strains from each sample were isolated to obtain a total of 180 strains, which were examined for resistance to ampicillin, chloramphenicol, cephalothin, doxycycline, ciprofloxacin, gentamicin, nitrofurantoin, and sulfisoxazole. The mean counts of Enterobacteriaceae from organic chicken meat were significantly higher than those obtained from conventional chicken (P < 0.0001) or conventional turkey (P < 0.0001) meat. However, the resistance data obtained showed that isolates from organic chicken meat were less resistant than isolates from conventional chicken meat to ampicillin (P = 0.0001), chloramphenicol (P = 0.0004), doxycycline (P = 0.0013), ciprofloxacin (P = 0.0034), gentamicin (P = 0.0295) and sulfisoxazole (P = 0.0442), and were less resistant than isolates from turkey meat to doxycycline (P = 0.0014) and sulfisoxazole (P = 0.0442). Multidrug resistant isolates were found in every group tested, but rates of multidrug resistant strains were higher in conventional chicken (63.3%) and turkey (56.7%) than organic chicken (41.7%) meat. The rates obtained for antimicrobial resistance support the theory that although organic chicken meat contains more Enterobacteriaceae contamination, organic farming practices contribute to decreased dissemination of antibiotic resistance.