Abundance of six tetracycline resistance genes in wastewater lagoons at cattle feedlots with different antibiotic use strategies

Abstract

The abundance of six tetracycline resistance genes tet(O), tet(Q), tet(W), tet(M), tet(B) and tet(L), were quantified over time in wastewater lagoons at concentrated animal feeding operations (CAFO) to assess how feedlot operation affects resistance genes in downstream surface waters. Eight lagoons at five cattle feedlots in the Midwestern United States were monitored for 6 months. Resistance and 16S-rRNA gene abundances were quantified using real-time PCR, and physicochemical lagoon conditions, tetracycline levels, and other factors (e.g. feedlot size and weather conditions) were monitored over time. Lagoons were sorted according to antibiotic use practice at each site, and designated as 'no-use', 'mixed-use' or 'high-use' for comparison. High-use lagoons had significantly higher detected resistance gene levels (tet(R); 2.8 x 10(6) copies ml(-1)) relative to no-use lagoons (5.1 x 10(3) copies ml(-1); P < 0.01) and mixed-use lagoons (7.3 x 10(5) copies ml(-1); P = 0.076). Bivariate correlation analysis on pooled data (n = 54) confirmed that tet(R) level strongly correlated with feedlot area (r = 0.67, P < 0.01) and 'total' bacterial 16S-rRNA gene level in each lagoon (r = 0.51, P < 0.01), which are both characteristic of large CAFOs. tet(M) was the most commonly detected gene, both in absolute number and normalized to 16S-rRNA gene level, although tet(O), tet(Q) and tet(W) levels were also high in the mixed and high-use lagoons. Finally, resistance gene levels were highly seasonal with abundances being 10-100 times greater in the autumn versus the summer. Results show that antibiotic use strategy strongly affects both the abundance and seasonal distribution of resistance genes in associated lagoons, which has implications on water quality and feedlot management practices.

Dissemination of veterinary antibiotics and corresponding resistance genes from a concentrated swine feedlot along the waste treatment paths

“…6b), while the correlation between the total TRGs and the total TCs was not significant. Similar results have been reported by previous studies (Gao et al, 2012;Luo et al, 2010;Mckinney et al, 2010;Peak et al, 2007). It is seen that the relatively high water solubility and stability of SAs tend to promote the spread of antibiotic resistance and also contribute to the strong correlation between SRGs and SAs in the aquatic environment (CheeSanford et al, 2009).…”

“…The presence of residual antibiotics could enhance the resistance level of microbial communities and promote the proliferation of antibiotic resistance genes (ARGs) in swine manure (Looft et al, 2012), livestock and poultry wastewater (Mckinney et al, 2010;Peak et al, 2007), farmland soil (Huang et al, 2013;Wu et al, 2010), and surface water (Graham et al, 2010;Luo et al, 2010). The residual antibiotics could promote the accumulation of ARGs even at subtherapeutic levels (Ghosh and Lapara, 2007).…”

Abundance and Diversity of Tetracycline Resistance Genes in Soils Adjacent to Representative Swine Feedlots in China

“…In theory, prevalent resistance genes in soils near swine feedlots should reflect the gastrointestinal microbes of the involved animals and the tendency of different genes (and/or their hosts) to survive after release into the environment (24). The prevalence of these four RPPs genes could be attributed to their predominance in the gastrointestinal tracts of pigs, as previously mentioned (30), and their elevated possibilities of transfer from one bacteria to another because of their close relationship with mobile genetic elements such as plasmids, conjugative transposons, integrons, and consequently their wide host range (16,32).…”

Abundance and Distribution of Tetracycline Resistance Genes and Mobile Elements in an Oxytetracycline Production Wastewater Treatment System

“…11 Additionally, ribosomal protection proteins (RPP) tet(O), tet(Q), and tet(W) have been found the most abundant in three United States STPs, 15 while RPP tet(M), tet(O), tet(Q), and tet(W) have been detected in high abundance in animal feedlot lagoons. 12,16 In our previous study, tet genes were detected in the majority of bacterial isolates from treated OTC production wastewater, with tet(A) and tet(C) being the most frequently detected. 10 The distribution of tet genes appears to vary among different environments, which may be associated with bacterial compositions, antibiotic levels, horizontal gene transfer, etc.…”