Antibiotic Resistance, Gene Transfer, and Water Quality Patterns Observed in Waterways near CAFO Farms and Wastewater Treatment Facilities

Abstract

We examined water quality indicators (pH, temperature, turbidity, total phosphorus, and fecal coliform density) and bacterial antibiotic resistance (prevalence, conjugative transfer, and genetic linkage of resistance elements) at locations impacted by confined animal feeding operations (CAFOs) and compared them to nearby reference sites. Sites located upstream and downstream of two wastewater treatment facilities were also compared. Sites near CAFO farms had poor water quality (elevated total phosphorus and turbidity), while water quality remained relatively good downstream of wastewater treatment plants. High proportions of antibiotic-resistant bacteria were observed at all study sites, and frequent conjugative transfer of resistance was observed in laboratory assays. Out of a total of 830 environmental bacterial isolates, 77.1% were resistant to only ampicillin, while 21.2% were resistant to combinations of antibiotics including ampicillin (A), kanamycin (K), chlorotetracycline (C), oxytetracycline (O), and streptomycin (S). Multi-drug-resistant bacteria were significantly more common at sites impacted by CAFO farms. In conjugation assays, 83.3% of the environmental isolates transferred one or more antibiotic resistance genes to a laboratory strain of Salmonella typhimurium. A subset of multi-drugresistant (A, C, and O) isolates was screened for specific tetracycline resistance genes and class I and II integrons. None of the screened isolates (n=22) were positive for integrons, while 13 isolates contained resistance genes for tet (B) and tet (C). Our results indicate that CAFO farms not only impair traditional measures of water quality but may also increase the prevalence of multi-drug-resistant bacteria in natural waters.

Fate and transport of tylosin-resistant bacteria and macrolide resistance genes in artificially drained agricultural fields receiving swine manure

“…Regardless, the transport of antibiotic resistance genes among different environmental compartments (e.g. soil, drainage water) might facilitate their spread among indigenous bacteria through horizontal gene transfer (West et al, 2010).…”

Presence of multi-drug resistant pathogenic Escherichia coli in the San Pedro River located in the State of Aguascalientes, Mexico

“…Spearman's rank correlation (West et al, 2011) was used to examine the relationships among temperature, pH, conductivity, dissolved oxygen, COD, BOD, total phosphorus, nitrogen, total solid suspended, mesophilic bacteria and total and fecal coliform density across all sample locations.…”

“…In the last decades, treated, and untreated wastewater have been released into natural streams leading to possible waterborne disease outbreaks resulting from the use of unsafe water for consumption, irrigation or recreational activities (Mazari-Hiriart et al, 2008; Chávez et al, 2011). Several studies on antibiotic resistant bacteria release and their occurrence in sewage and natural environments have been conducted (Sayah et al, 2005; Amábile-Cuevas et al, 2010; Chen et al, 2011; West et al, 2011; Czekalski et al, 2012; Sun et al, 2012; Tacão et al, 2012). However, the significance of rivers as environments providing irrigation water and recreational activities as well as the possibility of the potential spread of pathogenic and antibiotic resistant bacteria between the environment and humans and animals, marks them as highly relevant study subjects (Czekalski et al, 2012).…”

Fate and proliferation of typical antibiotic resistance genes in five full-scale pharmaceutical wastewater treatment plants

“…Thus, the emission of effluent and sludge represented a key route of release of ARGs into the receiving environment. For example, West et al (2011) detected a high abundance of ARGs in WWTP effluent receiving waters. Additionally, using dewatered sludge as land fertilizer also contributed to a high proportion of ARGs in soil, and the long half-life of ARGs in soil resulted in a higher persistence of antibiotic resistance (Burch et al, 2014).…”