Genetic Characterization of Antimicrobial-Resistant Escherichia coli Isolated from a Mixed-Use Watershed in Northeast Georgia, USA

Sohyun Cho, Hoang Anh Thi Nguyen, Jacob M. McDonald, Tiffanie A. Woodley, Lari M. Hiott, John B. Barrett, Charlene R. Jackson and Jonathan G. Frye
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Sohyun Cho: Department of Microbiology, University of Georgia, Athens, GA 30602, USA
Hoang Anh Thi Nguyen: Department of Microbiology, University of Georgia, Athens, GA 30602, USA
Jacob M. McDonald: Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
Tiffanie A. Woodley: Bacterial Epidemiology and Antimicrobial Resistance Research Unit, United States Department of Agriculture, Agricultural Research Service, U.S. National Poultry Research Center, Athens, GA 30605, USA
Lari M. Hiott: Bacterial Epidemiology and Antimicrobial Resistance Research Unit, United States Department of Agriculture, Agricultural Research Service, U.S. National Poultry Research Center, Athens, GA 30605, USA
John B. Barrett: Bacterial Epidemiology and Antimicrobial Resistance Research Unit, United States Department of Agriculture, Agricultural Research Service, U.S. National Poultry Research Center, Athens, GA 30605, USA
Charlene R. Jackson: Bacterial Epidemiology and Antimicrobial Resistance Research Unit, United States Department of Agriculture, Agricultural Research Service, U.S. National Poultry Research Center, Athens, GA 30605, USA
Jonathan G. Frye: Bacterial Epidemiology and Antimicrobial Resistance Research Unit, United States Department of Agriculture, Agricultural Research Service, U.S. National Poultry Research Center, Athens, GA 30605, USA

IJERPH, 2019, vol. 16, issue 19, 1-14

Abstract: In order to determine the role of surface water in the development and spread of antibiotic-resistant (AR) bacteria, water samples were collected quarterly from 2015 to 2016 from a mixed-use watershed in Georgia. In our previous study, 496 Escherichia coli were isolated from surface water, out of which, 34 isolates were resistant to antimicrobials. For the current study, these 34 AR E. coli were characterized using pulsed-field gel electrophoresis, AR gene detection, plasmid replicon typing, class I integron detection, and multi-locus sequence typing. Genes were identified as conferring resistance to azithromycin ( mph (A)); β-lactams ( bla CMY , bla CTX , bla TEM ); chloramphenicol ( floR ); streptomycin ( strA , strB ); sulfisoxazole ( sul1 , sul2 ); tetracycline ( tetA , tetB , tetC ); and trimethoprim/sulfamethoxazole ( dhfr5 , dhfr12 ). Five ciprofloxacin- and/or nalidixic-resistant isolates contained point mutations in gyrA and/or parC . Most of the isolates (n = 28) carried plasmids and three were positive for class I integrons. Twenty-nine sequence types (ST) were detected, including three epidemic urinary-tract-infection-associated ST131 isolates. One of the ST131 E. coli isolates exhibited an extended-spectrum β-lactamase (ESBL) phenotype and carried bla CTX-M-15 and bla TEM-1 . To our knowledge, this is the first study on the emergence of an ESBL-producing E. coli ST131 from environmental water in the USA, which poses a potential risk to human health through the recreational, agricultural, or municipal use of this natural resource. This study identified E. coli with AR mechanisms to commonly used antimicrobials and carrying mobile genetic elements, which could transfer AR genes to other bacteria in the aquatic environment.

Keywords: E. coli; surface water; antimicrobial resistance; extended spectrum β-lactamase (ESBL); ST131 (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2019
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