Investigation of antimicrobial resistance genes in organic fertilizers from animal residues

Animal wastes have been commonly reused in agriculture due to improve organic matter and nutritional input. However, organic animal fertilizers can be sources of antimicrobials, bacteria resistant to antimicrobials, and antimicrobial resistance genes. In this perspective, this work aimed to investigate the pr essence of antimicrobial resistance genes in organic animal wastes, such as fresh bovine manure from organic and conventional production systems, fresh and tanned organic poultry litter, conventional poultry litter tanned and bone meal. Sulfonamide resistance genes were detected in all residues. On the other hand, colistin and carbapenem resistance genes were not detected in any samples. A tetracycline resistance gene was detected in poultry litter. Quinolone resistance genes were detected in all samples, except bone meal. Despite the advantage of applying animal wastes in agricultural production, the existence of resistance genes in all residues, regardless of whether they come from organic or conventional systems, fresh or tanned, represents a public health risk since we can increase antimicrobial resistance genes in the soil which can favor the transfer to pathogenic bacteria of humans and animals.