Evaluation of levels of antibiotic resistance in groundwater-derived E. coli isolates in the Midwest of Ireland and elucidation of potential predictors of resistance

O’Dwyer, Jean; Hynds, Paul; Pot, Matthieu; Adley, Catherine C.; Ryan, Michael P.

Evaluation of levels of antibiotic resistance in groundwater-derived E. coli isolates in the Midwest of Ireland and elucidation of potential predictors of resistance | Evaluation des niveaux d’antibiorésistance des isolats d’E.coli en provenance des eaux souterraines du Centre Ouest Irlandais et explication des indicateurs potentiels de résistance Evaluación de los niveles de resistencia a antibióticos en agua subterránea derivado de los aislamientos de E. coli en el Medio Oeste de Irlanda y explicación de posibles predictores de resistencia 爱尔兰中西部源自地下水中大肠杆菌隔离群中抗菌素耐药性水平评估 Avaliação dos níveis de resistência antibiótica em E. coli isoladas derivadas de águas subterrâneas no Meio-Oeste da Irlanda e elucidação de pretitores de resistência potenciais

2017

O’Dwyer, Jean | Hynds, Paul | Pot, Matthieu | Adley, Catherine C. | Ryan, Michael P.

Antibiotic-resistant (pathogenic and non-pathogenic) organisms and genes are now acknowledged as significant emerging aquatic contaminants with potentially adverse human and ecological health impacts, and thus require monitoring. This study is the first to investigate levels of resistance among Irish groundwater (private wells) samples; Escherichia coli isolates were examined against a panel of commonly prescribed human and veterinary therapeutic antibiotics, followed by determination of the causative factors of resistance. Overall, 42 confirmed E. coli isolates were recovered from a groundwater-sampling cohort. Resistance to the human panel of antibiotics was moderate; nine (21.4%) E. coli isolates demonstrated resistance to one or more human antibiotics. Conversely, extremely high levels of resistance to veterinary antibiotics were found, with all isolates presenting resistance to one or more veterinary antibiotics. Particularly high levels of resistance (93%) were found with respect to the aminoglycoside class of antibiotics. Results of statistical analysis indicate a significant association between the presence of human (multiple) antibiotic resistance (p = 0.002–0.011) and both septic tank density and the presence of vulnerable sub-populations (<5 years). For the veterinary antibiotics, results point to a significant relationship (p = <0.001) between livestock (cattle) density and the prevalence of multiple antibiotic resistant E. coli. Groundwater continues to be an important resource in Ireland, particularly in rural areas; thus, results of this preliminary study offer a valuable insight into the prevalence of antibiotic resistance in the hydrogeological environment and establish a need for further research with a larger geological diversity.

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