Navigation

P1-161 Genomic Comparison of Extended Spectrum β-Lactamase-producing Bacteria Isolated from Beef Cattle Grazing on Pasture

Monday, August 1, 2016
America's Center - St. Louis
Sarah Markland, University of Florida, Gainesville, FL
Raies Mir, University of Florida, Gainesville, FL
Amber Ginn, University of Florida, Gainesville, FL
Kwangcheol Jeong, University of Florida, Gainesville, FL
Introduction: According to the Centers for Disease Control and Prevention, there are at least 2,049,224 illnesses and 23,000 deaths attributed to antibiotic resistance each year. In 2003, the Food and Agriculture Organization and World Health Organization released a statement indicating that the major transmission pathway of resistant bacteria and their genes from the agricultural environment to humans is through consumption of food-producing animals. 

Purpose: The purpose of this study was to compare antibiotic resistance genes, specifically extended-spectrum β-lactamase (ESBL) genes, among bacteria isolated from commercial beef farms in North Florida.

Methods: Fecal samples were collected from two separate cohorts of multi-breed beef calf populations derived of Brahman and Angus cattle in 2013 and 2014. Neither set of calves had been previously exposed to antibiotics. Fecal samples were serially diluted and plated on MacConkey Agar containing 4 µg/ml cefotaxime to isolate ESBL-producing bacteria. Whole genome sequencing (WGS) of 31 isolated cefotaxime resistant bacterial isolates from cattle was performed using the Illumina MiSeq. De novo genome assembly was performed using Patric and whole genomes were annotated using RAST.  

Results: WGS revealed that the major bacterial species represented by resistant bacteria isolated from farms was Escherichia coli (60%) followed by Shigella flexneri (20%). The majority of isolates from 2013 were found to contain the blaCTX-M-1 gene while 2014 isolates were found contain blaCTX-M-32 genes. In addition, all isolates from 2014 were found to be multi-drug resistant compared to 11.8% of isolates from 2013.

Significance: The results of this study demonstrate the high levels of antibiotic resistant organisms shed by cattle not previously exposed to antibiotics. This study also shows the evolution of antibiotic resistance in bacterial populations in food-producing animals over time.

Back to: Poster Session 1 – Produce, Meat, Poultry and Eggs, Non-microbial Food Safety; Laboratory and Detection Methods; Communication Outreach and Education; Seafood; Antimicrobials; Food Toxicology
<< Previous Abstract | Next Abstract >>