Emergence of resistance genes in fecal samples of antibiotic-treated Philippine broilers emphasizes the need to review local farming practices

Abstract

The poultry industry is a major contributor to the Philippine economy. Given the rising concerns in antibiotic resistance and food security, farmers need to maximize profit and output while ensuring safe and ecologically sustainable farming practices. This study surveyed antibiotic use in 12 commercial poultry farms in the Philippines. All farms reported the use of medically important antibiotics either for prophylaxis (91.67%), metaphylaxis (100%), and growth promotion (50%). Considering the widespread use of medically important antibiotics, we then investigated the potential contribution of local antibiotic treatment protocols to the emergence of antibiotic resistance genes in the fecal samples of broiler chickens under a controlled experimental setup. Significantly, we observed the emergence of antibiotic resistance genes (ermB) in fecal samples of antibiotic-treated broilers after 7 days and 21 days in antibiotic-free broilers raised in the same farming environment. These data were corroborated by antibiotic resistance gene profiles of fecal samples from commercial poultry farms. Antibiotic resistance genes (tetA, tetB, tetU, tetW, qnrB, qnrS) were prevalent in the fecal samples of antibiotic-treated broilers treated with tetracycline and quinolone antibiotics. Therefore, our study provides concrete evidence for the strong correlation between the use of medically important antibiotics in poultry farming and the emergence of antibiotic resistance genes. Antimicrobial resistance is a major contributor to failures in infectious disease treatment strategies in humans and animals. Therefore, the cost-benefit ratio of poorly regulated antibiotic treatment protocols in poultry farming could have a long-term detrimental impact on our economy and public health. Our study suggests the need to review our current policies and practices in using medically important antibiotics in the Philippine poultry industry.