Antibiotics and microbial resistance in Brazilian soils under manure application

Abstract

AbstractAnimal manure is commonly used in agriculture as fertiliser. This practice could represent, however, a risk of soil degradation through the accumulation of pharmaceutical residues or resistant microorganisms. Thus, 12 pharmaceuticals (11 antibiotics and 1 nonsteroidal anti‐inflammatory drug) were quantified in soil samples from 15 sites regularly fertilised with different animal manures (dairy cow, pig or poultry litter manure) and from forest sites in southern Brazil. This study (a) investigated the impacts of Brazilian animal waste application on antibiotic levels and induced bacterial resistance of soils and (b) determined whether one type of waste is more polluting than others. Three bacterial resistance genes, namely, sul1, qnr A, and erm, were also quantified to determine the impacts of manure application on the resistance of soil microbial communities. The effect of manure application was confirmed by the presence of antibiotic residues (up to 38.3 μg kg−1) and bacterial resistance modifications of the bacterial community (up to 8.97 × 10−3 copies of genes per bacteria) in the studied soils. Soils amended with pig manure presented the highest antibiotic concentrations. However, soils subjected to dairy cow grazing over long periods of time presented the highest concentrations of sulfonamide resistance gene (sul1). Our results lead us to infer that the type of manure can induce a “specific pollution fingerprint.”