Plasmid-Mediated Quinolone Resistance Genes and Antibiotic Residues in Wastewater and Soil Adjacent to Swine Feedlots: Potential Transfer to Agricultural Lands

Abstract

Background: Inappropriate use of antibiotics in swine feed could cause accelerated emergence of antibiotic resistance genes, and agricultural application of swine waste could spread antibiotic resistance genes to the surrounding environment.Objectives: We investigated the distribution of plasmid-mediated quinolone resistance (PMQR) genes from swine feedlots and their surrounding environment.Methods: We used a culture-independent method to identify PMQR genes and estimate their levels in wastewater from seven swine feedlot operations and corresponding wastewater-irrigated farm fields. Concentrations of (fluoro)quinolones in wastewater and soil samples were determined by ultra-performance liquid chromatography–electrospray tandem mass spectrometry.Results: The predominant PMQR genes in both the wastewater and soil samples were qnrD, qepA, and oqxB, whereas qnrS and oqxA were present only in wastewater samples. Absolute concentrations of all PMQR genes combined ranged from 1.66 × 107 to 4.06 × 108 copies/mL in wastewater and 4.06 × 106 to 9.52 × 107 copies/g in soil. Concentrations of (fluoro)quinolones ranged from 4.57 to 321 ng/mL in wastewater and below detection limit to 23.4 ng/g in soil. Significant correlations were found between the relative abundance of PMQR genes and (fluoro)quinolone concentrations (r = 0.71, p = 0.005) and the relative abundance of PMQR genes in paired wastewater and agricultural soil samples (r = 0.91, p = 0.005).Conclusions: Swine feedlot wastewater may be a source of PMQR genes that could facilitate the spread of antibiotic resistance. To our knowledge, this is the first study to examine the occurrence of PMQR genes in animal husbandry environments using a culture-independent method.

Prevalence and Characterisation of Non-Cholerae Vibrio spp. in Final Effl uents of Wastewater Treatment Facilities in Two Districts of the Eastern Cape Province of South Africa: Implications for Public Health

“…It has been some years since Iwane and colleagues [23] showed that the increase of antibiotic resistant bacteria in the Tama River was associated with WWTP effluent discharges. Since then, a wide range of genetic methods have been developed and some culture-independent studies have been performed to explore the impact of antibiotics in the environment; however, most of these studies have been limited to a few ARGs [24][25][26].…”

Functional metagenomic characterization of antibiotic resistance genes in agricultural soils from China

“…Some of the ARGs were closely linked with a number of widespread mobile genetic elements (MGEs), including plasmids, transposons and integrons, which were involved in horizontal transfer of ARGs among environmental bacteria (Fluit and Schmitz, 1999;Fricke et al, 2009;Li et al, 2012;. These ARGs could be missed when screening a microbial chromosomal DNA derived metagenomic library.…”

Antibiotic resistance genes occurrence and bacterial community composition in the Liuxi River

“…Riverine ARGs were correlated with human activities (Pruden et al, 2012). Evidences suggested that human affecting compartments, such as wastewater treatment plants, animal feedlots and pharmaceutical factories were as significant point sources of ARGs into the receiving water bodies (Graham et al, 2010;LaPara et al, 2011;Li et al, 2012), which may also explain the reason why high contaminations of ARGs were observed in the Liuxi River. Besides antibiotics, metals also co-select for ARGs (Knapp et al, 2011).…”