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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #383469

Research Project: Intestinal Microbial Ecology and Metagenomic Strategies to Reduce Antibiotic Resistance and Foodborne Pathogens

Location: Food Safety and Enteric Pathogens Research

Title: Antibiotic resistance horizontal gene transfer from the commensal microbiota to Salmonella enterica Serovar Heidelberg, in the chicken gastrointestinal tract

item Looft, Torey
item KLIMA, CASSIDY - Iowa State University
item MAKI, JOEL - Orise Fellow
item Trachsel, Julian
item JOHNSON, TIMOTHY - Purdue University
item Oladeinde, Adelumola - Ade
item GUERNIER, VANINA - Orise Fellow
item Bearson, Shawn
item SYLTE, MATTHEW - Animal And Plant Health Inspection Service (APHIS)

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/24/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Antimicrobial resistance (AMR) in human pathogens has become a significant problem to treat infections. AMR Salmonella is a serious concern, as is the need to reduce the rate of transfer of genetic material between commensals and pathogens. The objective of this study was to determine the antibiotic resistance genes that are enriched in the poultry gut microbiome due to antimicrobial use, identify the hosts of AMR, and determine which AMR genes are acquired by Salmonella enterica serovar Heidelberg SH2813. One hundred seventy-eight one day-old chicks were split between 3 rooms and orally inoculated with 2X10^8 cfu of nalidixic acid resistant Salmonella. After one week, diets were amended to include either 50 g/ton Bacitracin Methylene Disalicylate (BMD), elevated zinc (240 mg/kg), or continued on non-medicated feed. Ten birds from each group were euthanized at 1, 2, 4, and 6 weeks of age, and cecal contents were collected for total Salmonella enumeration as well as determination of acquired tetracycline or ampicillin resistance. Salmonella initially colonized chicks at high levels, but declined with each subsequent sampling timepoint. A high percent of the Salmonella recovered were tetracycline resistant regardless of treatment group, including before medications were added to the feed. Plasmid and genomic DNA was isolated from resistant Salmonella and was sequenced using both the Nanopore MinION and Illumina HiSeq. Ongoing research aims to explore the genetic diversity of the antibiotic resistance determinants acquired by Salmonella from the microbiota. Understanding factors that contribute to commensal bacteria transferring resistance genes to pathogens will inform interventions to slow this process.