Antibiotic susceptibility profiles of soil Escherichia coli isolated from conventional and local poultry settings.

Abstract

Poultry production is increasing globally to meet the rising demand for meat and eggs, leading to widespread antibiotic use in conventional poultry farming to boost yield. Since these antibiotics are not fully metabolized, residues are excreted in chicken droppings and can biomagnify in the food chain, impacting consumer health and soil ecosystems. Local poultry farming, common in countries like Nigeria, avoids routine antibiotic use, yet birds in these systems often scavenge in wastewater outlets and dumpsites that may contain remains of household chemicals such as sanitizers and disinfectants, which usually contain compounds like triclosan and quaternary ammonium compounds that may induce antibiotic resistance due to structure-activity relationships with other antibiotics. Both antibiotic residues and these co-selecting compounds have previously been shown to promote the proliferation and horizontal transfer of antibiotic resistance genes (ARGs) in soil bacteria. Furthermore, the extensive use of poultry manure in agriculture raises concerns about outbreaks caused by contamination with antibiotic-resistant bacteria. Our study compared Escherichia coli isolates from soils receiving conventional poultry manure, local poultry droppings, and control sites. We observed differences in susceptibility profiles of isolates between all the sites, although the susceptibility is only statistically significant in conventional poultry soils compared to control sites. These findings suggest that, while conventional poultry practices exert a strong selective pressure on soil bacteria, organic systems also contribute to ARG dissemination. Consequently, our results highlight the need for prudent antibiotic use, improved waste management practices, and the implementation of closed, monitored organic poultry systems to mitigate the spread of antimicrobial resistance.