Effects of swine manure on macrolide, lincosamide, and streptogramin B antimicrobial resistance in soils

Abstract

Current agricultural practices involve inclusion of antimicrobials in animal feed and result in manure containing antimicrobials and antimicrobial-resistant microorganisms. This work evaluated the effects of land application of swine manure on the levels of tetracycline, macrolide, and lincosamide antimicrobials and on macrolide, lincosamide, and streptogramin B (MLSB) resistance in field soil samples and laboratory soil batch tests. MLSB and tetracycline antimicrobials were quantified after solid-phase extraction using liquid chromatography-tandem mass spectrometry. The prevalence of the ribosomal modification responsible for MLSB resistance in the same samples was quantified using fluorescence in situ hybridization. Macrolide antimicrobials were not detected in soil samples, while tetracyclines were detected, suggesting that the latter compounds persist in soil. No significant differences in ribosomal methylation or presumed MLSB resistance were observed when amended and unamended field soils were compared, although a transient (