Irrigation Ponds as Sources of Antimicrobial-Resistant Bacteria in Agricultural Areas with Intensive Use of Poultry Litter

Abstract

Poultry litter is widely used worldwide as an organic fertilizer in agriculture. However, poultry litter may contain high concentrations of antibiotics and/or antimicrobial-resistant bacteria (ARB), which can be mobilized through soil erosion to water bodies, contributing to the spread of antimicrobial resistance genes (ARGs) in the environment. To better comprehend this kind of mobilization, the bacterial communities of four ponds used for irrigation in agricultural and poultry production areas were determined in two periods of the year: at the beginning (low volume of rainfall) and at the end of the rainy season (high volume of rainfall). 16S rRNA gene sequencing revealed not only significantly different bacterial community structures and compositions among the four ponds but also between the samplings. When the DNA obtained from the water samples was PCR amplified using primers for ARGs, those encoding integrases (intI1) and resistance to sulfonamides (sul1 and sul2) and β-lactams (blaGES, blaTEM and blaSHV) were detected in three ponds. Moreover, bacterial strains were isolated from CHROMagar plates supplemented with sulfamethoxazole, ceftriaxone or ciprofloxacin and identified as belonging to clinically important Enterobacteriaceae. The results presented here indicate a potential risk of spreading ARB through water resources in agricultural areas with extensive fertilization with poultry litter.

On composite sampling for monitoring generic and antibiotic-resistant coliforms in irrigation ponds

“…Information regarding fine-scale variations in AMR in small waterbodies is usually constrained to urban, aquaculture, or wastewater treatment ponds where sampling of the influent, midpoint, and effluent are common but, in many cases, only a single sample is collected per sampling date (Tendencia and de la Peña, 2001;Mispagel and Gray, 2005;McKinney et al, 2010;Harmon et al, 2019;Craddock et al, 2020;Hou et al, 2021). In the cases where multiple samples are collected, they are often composited prior to analysis or have the results pooled during data analysis which makes determining the spatial variation across the waterbody impossible (e.g., Lopes et al, 2022;Yoneda et al, 2022). More work is needed to elucidate the spatial variation in AMR in not only irrigation waters but other surface waters as well as the collection of a single sample may result in the under-or overestimation of antibiotic microorganisms or genes present in a waterbody.…”