Unexpected Prevalence of eae-Positive Escherichia coli in the Animas River, Durango, Colorado.

Steve Hamner,Benjamin T Nance,Timothy E Ford,Kami S Parrish-Larson,Steven D Fenster,Michael W Morrow,Katherine A Mclain

doi:10.3390/ijerph17010195

Abstract

Since 2014, biology students at Fort Lewis College have studied the water quality of the Animas River in Durango, Colorado. Environmental microbiology and molecular biology techniques have been employed to study Escherichia coli isolates from the river and to define characteristics of the bacteria related to public health. E. coli was found in the river, as well as in culverts and tributary creeks that drain into the river within the Durango city limits. Concentrations of E. coli in the river occasionally exceeded the US EPA guideline of 126 CFU per 100 mL for recreational water use. Many of the E. coli isolates were able to be grown at 45 °C, an indication of mammalian origin. Unexpectedly, 8% of the isolates contained the intimin (eae) gene, a virulence gene characteristic of two pathotypes of E. coli, the enterohemorrhagic and enteropathogenic E. coli. Several isolates tested were resistant to multiple antibiotics commonly used in animal and human medicine. Further study is warranted to determine the source of these bacteria entering the Animas River, and to further characterize the possible disease potential of multi-antibiotic resistant and virulence gene-containing isolates found in a semi-rural/urban setting.

Highlights

From its headwaters in the San Juan Mountains in southwest Colorado, the Animas River flows south through Silverton, a historic mining town, and Durango, a city having origins in the mining industry and currently popular as a center for outdoor recreation and tourism
During the period August 2014 through February 2015, a total of fifteen samples were collected from the Animas River sites and tested for E. coli concentrations (Figure 2)
E. coli concentrations at the skateboard park drain site exceeded 126 CFU per 100 mL on three of the six sampling dates, but the site is of lesser concern in terms of direct human exposure as it is not classified for recreational water use

Summary

Introduction

From its headwaters in the San Juan Mountains in southwest Colorado, the Animas River flows south through Silverton, a historic mining town, and Durango, a city having origins in the mining industry and currently popular as a center for outdoor recreation and tourism. The Animas River is heavily utilized for recreational activities, including swimming, rafting, and fishing. A segment of the river near Durango is designated a “gold medal” fishing destination [1], a label given to streams producing large numbers of trophy trout. Recreational use of the river has a significant economic impact. On the lower Animas River in the Durango area, a 2006 study estimated that whitewater recreation contributed over $19 million to the local economy annually [2]

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Conclusion