Third-generation cephalosporin- and tetracycline-resistant escherichia coli and antimicrobial resistance genes from metagenomes of mink feces and feed

Authors: Agga, Getahun; Silva, Philip - Phil; MARTIN, RANDAL - Utah State University

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2020
Publication Date: 10/20/2020
Citation: Agga, G.E., Silva, P.J., Martin, R.S. 2020. Third-generation cephalosporin- and tetracycline-resistant escherichia coli and antimicrobial resistance genes from metagenomes of mink feces and feed. Foodborne Pathogens and Disease. 18(3):169-178. https://doi.org/10.1089/fpd.2020.2851.
DOI: https://doi.org/10.1089/fpd.2020.2851

Interpretive Summary: Antimicrobial resistance (AMR) is a global problem affecting animals and humans and the environment. Mink production plays a significant role in the global fur industry. Like food animal production systems, mink farming also depends on antibiotics to treat diseases and to ensure the well-being of the animals. However, little is known about AMR bacteria in mink farms. This study revealed that similar levels of bacteria resistant to medically important antimicrobials, as from food animals, can be found in mink farms. Feed samples also contained AMR bacteria and genes indicating the importance of quality animal feed in the control of infections and AMR in mink production. Proper waste management at mink farms may aid to limit the spread of AMR bacteria into the environment.

Technical Abstract: American mink (Neovison vison) is a significant source of global fur production. Except for a few studies from Denmark and Canada reporting antimicrobial resistance in bacteria isolated from clinical cases, studies from the general mink population are scarce and absent in the United States. Mink feces (n = 42) and feed (n = 8) samplesobtained from a mink farm were cultured for the enumeration and detection of tetracycline-resistant (TETr)- and third-generation cephalosporin-resistant (TGCr)-Escherichia coli. Isolates were characterized phenotypically for their resistance to other antibiotics and genotypically for resistance genes. TETr E. coli were detected from 98% of feces samples (mean concentration = 6 log10) and from 100% of feed samples (mean concentration = 3.2 logs). Among TETr E. coli isolates, 44% (n = 41) of fecal- and 50% (n = 8) of feed isolates were multidrug resistant (MDR; resistance to ‡3 antimicrobial classes), and 96% (n = 49) of TETr isolates were positive for tet(A) and/or tet(B). TGCr E. coli were detected from 95% of feces and 75% of feed samples with 78% (n = 40) of fecal isolates, and all six of the feed isolates were MDR. Nearly two-thirds (65%) of the TGCr E. coli isolates(n = 46) were positive for blaCMY-2; the remaining 35% were positive for blaCTX-M, with the blaCTX-M-14 being the predominant (75%, n = 16) variant detected. Metagenomic DNA was extracted directly from feces and feed samples, and it was tested for 84 antimicrobial resistance genes by using quantitative polymerase chain reaction (PCR) array; selected genes were also quantified by droplet digital PCR. The genes detected from the fecal samples belonged mainly to five antimicrobial classes: macrolide–lincosamide–streptogramin B (MLSB; 100% prevalence), TETs (88.1%), b-lactams (71.4%), aminoglycosides (66.7%), and fluoroquinolones (47.6%). b-Lactam, MLSB, and TET resistance genes were also detected from feed samples. Our study serves as a baseline for further studies and to streamline antimicrobial use in mink production in accordance with current regulations as in food animals.