Surveillance for Antibiotic-Resistant E. coli in the Salish Sea Ecosystem.

Alexandria Vingino,Ryan Ruiz,Stephanie A Norman,Michelle Wainstein,Marilyn C Roberts,Dyanna Lambourn,Peter Rabinowitz,James West,Jeffery Lahti,Scott J Weissman,Marisa D’Angeli

doi:10.3390/antibiotics10101201

Abstract

E. coli was isolated from the Salish Sea (Puget Sound) ecosystem, including samples of marine and fresh water, and wildlife dependent on this environment. E. coli isolates were assessed for phenotypic and genotypic resistance to antibiotics. A total of 305 E. coli isolates was characterized from samples collected from: marine water obtained in four quadrants of the Salish Sea; select locations near beaches; fresh water from streams near marine beaches; and fecal samples from harbor porpoises (Phocoena phocoena), harbor seals (Phoca vitulina), river otters (Lontra canadensis), and English sole (Parophrys vetulus). Isolates were evaluated using antimicrobial susceptibility typing, whole-genome sequencing, fumC, and multilocus sequence typing. Resistance and virulence genes were identified from sequence data. Of the 305 isolates from Salish Sea samples, 20 (6.6%) of the E. coli were intermediate, and 31 (10.2%) were resistant to ≥1 class of antibiotics, with 26.9% of nonsusceptible (resistant and intermediate resistant) E. coli isolates from marine mammals and 70% from river otters. The proportion of nonsusceptible isolates from animals was significantly higher than samples taken from marine water (p < 0.0001). A total of 196 unique STs was identified including 37 extraintestinal pathogenic E. coli (ExPEC)-associated STs [ST10, ST38, ST58, ST69, ST73, ST117, ST131, and ST405]. The study suggests that animals may be potential sentinels for antibiotic-resistant and ExPEC E. coli in the Salish Sea ecosystem.

Highlights

The anthropogenic use of antibiotics in clinical, agricultural, and community settings has contributed to the spread of antibiotic-resistant bacteria (ARB) throughout the world, affecting many ecosystems [1]
A total of 212 E. coli isolates was analyzed for resistance from the four quadrants of marine water
Looking solely at the difference of proportion of resistant and intermediate isolates in marine mammals and marine water, the analysis determined that there was a higher number of nonsusceptible isolates, when the E. coli came from a marine mammal source (p = 0.005)

Summary

Introduction

The anthropogenic use of antibiotics in clinical, agricultural, and community settings has contributed to the spread of antibiotic-resistant bacteria (ARB) throughout the world, affecting many ecosystems [1]. We report on an exploratory study characterizing multiple samples from the Salish Sea ecosystem including water and animals to determine the level of antibiotic-resistant E. coli within various sources throughout the Salish Sea environment and its wildlife. E. coli has a large number of sequence types (STs) identified using multilocus sequence type methods (MLST) [7], many of which have been described in terms of pathogenesis and virulence. It has a number of well-characterized antimicrobial-resistance genes (https://ege.cbs.dtu.dk accessed on 1 March 2021) and virulence factors [8]

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Discussion

Conclusion