title: Patterns of Multi-Antibiotic-Resistant Escherichia Coli from Streams with No History of Antimicrobial Inputs.
abstract: A growing body of evidence suggests that contaminated environments may harbor a greater proportion of antibiotic-resistant microorganisms than unpolluted reference sites. Here, we report the screening of 427 Escherichia coli strains isolated from 11 locations on nine streams draining the US Department of Energy's Savannah River Site against a panel of five antibiotics. Streams were chosen to capture a wide range of watersheds from minimally disturbed to highly impacted. Overall, higher levels of resistance were found in waterborne E. coli that also generally exhibited low spatial variability. However, 3 of 11 locations also demonstrated elevated resistance levels in sediments. Two of these occurred in highly disturbed tributaries with no obvious sources of antimicrobials. To further investigate these patterns, we screened a subset of isolates obtained from three streams against 23 antibiotics or antibiotic combinations. A large proportion of these isolates (>40 %) demonstrated resistance to 10 or more antimicrobials, suggesting that environmental multi-antibiotic resistance may be prevalent in this bacterial commensal. Only 4 of 87 viable isolates were tested susceptible to all 23 antibiotics and combinations. Among these multi-antibiotic-resistant isolates, several demonstrated resistance to all structural classes of antimicrobial agents tested, including frontline antibiotics such as gatifloxacin and ciprofloxacin.
authors.affiliation: Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC, 29802, USA. mcarthur@srel.edu.
authors.forename: J V
authors.identifier: 0000-0002-9892-9744
authors.initials: JV
authors.lastname: McArthur
authors.affiliation: Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC, 29802, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Fletcher
authors.affiliation: Ecostatys, LLC, Aiken, SC, USA.
authors.forename: R Cary
authors.initials: RC
authors.lastname: Tuckfield
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science, Weymouth, Dorset, UK.
authors.forename: C
authors.initials: C
authors.lastname: Baker-Austin
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D004338:Drug Combinations; D024901:Drug Resistance, Multiple, Bacterial / Q000502:physiology*; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D024841:Fluoroquinolones / Q000494:pharmacology; D000077734:Gatifloxacin; D019015:Geologic Sediments / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D045483:Rivers / Q000382:microbiology*; D014871:Water Microbiology; D018440:beta-Lactam Resistance / Q000235:genetics; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D024841:Fluoroquinolones; D047090:beta-Lactams; D002939:Ciprofloxacin; D000077734:Gatifloxacin
keywords: Antibiotic resistance; E. coli; Industrial activity