Antibiotic resistance gene occurrence in poultry farms in northeast Brazil

The misuse of antibiotics in food-producing animal farming practices exerts selective pressure on bacterial strains, intensifying the spread of pathogenic and commensal bacteria carrying antibiotic resistance genes (ARGs). We conducted a study aiming to investigate ARGs in chicken litter from farms in the State of Sergipe, Northeast Brazil. A total of 14 chicken litter samples were collected from twelve farms and subjected to total DNA extraction. The presence of ARGs in the obtained material was tested by Polymerase Chain Reaction (PCR) using primers for selected ARGs. ARGs were confirmed in all samples, and the highest resistance positivity was obtained for tetracyclines (tetA, tetM, and tetG), quinolones (gyrA and qnrS), beta-lactams (blaTEM), macrolides (ermB) and sulfonamides (sul-1 ). Sequencing and comparison with the GenBank database confirmed the identity of the ARGs. Some of the sequences that were amplified by PCR were similar to resistance factors found in Gram-positive and Gram-negative bacteria of different species, mostly enterobacteria. Furthermore, similarity was observed for resistance determinants located both on the chromosome and on plasmids, transposons, and integrons. Our results indicate the potential of poultry farming for the environmental dissemination of ARGs in the State of Sergipe.

Keywords:
Antibiotic-resistant bacteria; poultry manure; environmental dissemination; antimicrobial; avian