Elevated incidences of antimicrobial resistance and multidrug resistance in the Maumee River (Ohio, USA), a major tributary of Lake Erie

Authors: MUKHERJEE, MAITREYEE - University Of Southern Mississippi; KOCIAN, LEAH - Texas A&M University; LILES, CHEYENNE - Texas A&M University; MUSTAFA, NADIA - Bowling Green State University; BULLERJAHN, GEORGE - Bowling Green State University; GENTRY, TERRY - Texas A&M University; Brooks, John

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2021
Publication Date: 4/24/2021
Citation: Mukherjee, M., Kocian, L., Liles, C., Mustafa, N., Bullerjahn, G., Gentry, T., Brooks, J.P. 2021. Elevated incidences of antimicrobial resistance and multidrug resistance in the Maumee River (Ohio, USA), a major tributary of Lake Erie. Microorganisms. 9(5): 911. https://doi.org/10.3390/microorganisms9050911.
DOI: https://doi.org/10.3390/microorganisms9050911

Interpretive Summary: The Maumee River in Ohio is subject to many sources of agriculture and municipal contamination before it arrives at Lake Erie. As it passes through these areas, it can pick up bacteria, such as fecal bacterial indicators like E. coli, which in many cases will carry antimicrobial resistance. Given the recent concerns associated with antimicrobial resistance, understanding the environmental sources of bacteria like E. coli can inform public health and municipalities about potential risks in freshwater sources. The current study aimed to address the potential impact of antimicrobial resistant E. coli in the Maumee river, collecting samples monthly from four different locations prior to entering Lake Erie. Resistance profiles were developed using standard plate methods. Nearly all isolates were resistant to at least 1 antibiotic, which was not surprising. In addition, many of the isolates were multi-drug resistant, however, resistance was associated with similar acting antibiotics. There were no trends associated with sampling location, however sampling month did affect the amount of resistance and presence of select bacteria in the freshwater source. The study has potential to inform risk managers identifying locations for further interventions.

Technical Abstract: The occurrence and prevalence of antimicrobial resistance (AMR) and multidrug resistance (MDR) among pathogenic microorganisms have emerged as a profound threat to life on this planet by increasingly compromising the treatment of life-threatening diseases globally. Although many studies have focused on determining spread of AMR and MDR from clinical and farm environments, very little is known about environmental and natural reservoirs of AMR and MDR in rivers and lakes, and the impact of agriculture and urbanization on this. Maumee River, the major tributary in the western basin of Lake Erie, serves as one of major sources of freshwater in the area supplying potable, recreational, and industrial water as it drains into the western basin of Lake Erie near the city of Toledo. Although a lot of research has focused on the pervasive occurrence of periodic harmful algal blooms in the river each year, no study thus far has been directed to look at the prevalence of coliform bacteria, AMR and MDR in the river. Therefore, studying the occurrence of AMR and MDR in this watershed is very important because of the likely manifold implications it has on public health, agricultural, industrial and environmental regulations. In this study we collected water samples from four different sites in the Maumee River bay between 2016-2017. From these samples, a total of 375 strains of E.coli were isolated, enumerated, and analyzed for AMR and MDR by antimicrobial sensitivity testing using the Kirby-Bauer disk-diffusion method for multiple antibiotics: tetracycline, imipenem, cephalothin, gentamicin, sulfamethoxazole, ciprofloxacin, cefoperazone and ampicillin. Strikingly, 95% of the total isolates were found to be resistant to at least one antibiotic or more. A very high resistance to the drugs cephalothin (95.3%), ampicillin (38.3%), tetracycline (8.8%), gentamicin (8.2%), ciprofloxacin (4.2%), cefoperazone (4%), and sulfamethoxazole (1.5%) was observed within isolates from all four sampling sites across all sampling events. Across all the months sampled, the percentage of AMR and MDR was found to be consistently very high in the summer and fall months (October and November 2016, May, June and July 2017), whereas it was observed to be lowest in the winter (December 2016). A remarkably high number of the isolates were detected to be MDR – 95% resistant to =1 antibiotic, 43% resistant to =2 antibiotics, 15% resistant to =3 antibiotics, 4.9% resistant to =4 antibiotic and 1.2% resistant to =5 antibiotic. This data will serve in better understanding the environmental occurrence and dissemination of AMR/MDR in the area and assist in improving and establishing control measures.