Prevalence and characterization of Escherichia coli isolated from the Upper Oconee Watershed in Northeast Georgia

Abstract

Surface waters are important sources of water for drinking, industrial, agricultural, and recreational uses; hence, contamination of water by fecal, pathogenic, or antimicrobial resistant (AR) bacteria is a major environmental and public health concern. However, very little data is available on prevalence of these bacteria in surface water throughout a watershed. This study aimed to characterize Escherichia coli present in the Upper Oconee Watershed, a mixed-use watershed in Athens, GA, USA for potential pathogenicity and AR. E. coli were enumerated by colony counts, cultured by enrichment and direct plating, and characterized by phylo-groups, diarrheagenic pathotypes, and antimicrobial susceptibility. From the analysis, 99.3% (455/458) of the total samples were positive for E. coli resulting in 496 isolates. E. coli counts were as high as 1.2×104 CFU/100 ml, which is above the United States Environmental Protection Agency (U.S. EPA) threshold for recreational water (235 CFU/100 ml based on a one-time measurement). Phylo-groups B2 (31.7%; 157/496) and B1 (30.8%; 153/496) were the most prevalent among the isolates. Enteropathogenic E. coli (EPEC) (19/496) and Shiga toxin-producing E. coli (STEC) (1/496) were the only diarrheagenic pathotypes detected. AR was observed in 6.9% (34/496) of the isolates, 15 of which were multidrug resistant (MDR; resistance to two or more classes of antimicrobials). Tetracycline resistance was most often detected (76.5%; 26/34), followed by ampicillin (32.4%; 11/34), streptomycin (23.5%; 8/34), sulfisoxazole (23.5%; 8/34), and nalidixic acid (14.7%; 5/34). Results from this study showed that E. coli is prevalent in high levels in the Upper Oconee Watershed, suggesting possible widespread fecal contamination. The presence of pathogenic, AR E. coli in the watershed indicates that environmental water can serve as a reservoir of resistant bacteria that may be transferred to humans through drinking and recreational activities.

Diversity and antimicrobial resistance of Enterococcus from the Upper Oconee Watershed, Georgia

“…and the exact locations of the sites, along with the GPS coordinates, are in Table . Interestingly, a complimentary study conducted on the same sampling sites showed that Enteropathogenic E. coli and AR E. coli isolates were recovered from 22 of the 35 MDR Enterococcus ‐positive sites (Cho et al ). This finding shows that there are sites within the Upper Oconee watershed that contribute towards the spread of pathogenic and AR bacteria.…”

“…Filtration and enrichment of water samples were performed as previously described (Cho et al ). Briefly, 0·5 g of cellulose filter powder (Aqua Dew ™ , Lahore, Pakistan) was added to water samples (1 L), which was then filtered onto 47‐mm glass fibre filters (Pall Corporation, Ann Arbor, MI).…”

Reaching a Large Urban Undergraduate Population through Microbial Ecology Course-Based Research Experiences

“…The investigative process for the Urban Water Quality course includes the common methods used by monitoring and regulatory agencies. Urban watersheds are under increasing pressure due to population growth and land development, with a strong impact on the microbial community (28,29). Students select local water resources to sample, which removes a bias for neighborhoods with greater financial or political interest that can be present for typical monitoring programs.…”

Antibiotics resistant Escherichia coli isolated from aquatic ecosystems in Palembang, South Sumatra, Indonesia

“…Jain (2019) reported that the Ganga river had been polluted by a large number of resistant antibiotics bacteria which was suspected from some waste discharged from households, drug manufacturing units, hospitals, and poultry industries. Another study was done by Cho et al (2018) suggested that the other possible human's coliform sources include sewage leaks, failing septic tanks, municipal, residential, medical, and industrial waste facilities and also animal sources include runoffs from animal farms, land application of animal manure, pet wastes from parks, and wildlife; all of them are potentially increase the spreads of the hazardous contaminants.…”