Abstract #T168

Section: Food Safety
Session: Food Safety
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Gatlin Ballroom
# T168
Metagenomic evidence of the prevalence and distribution patterns of antimicrobial resistant genes in dairy agroecosystems.
Dipti Pitta*1, Sanjay Kumar1, Nagaraju Indugu1, Zhengxia Dou1, John Toth1, Bonnie Vecchiarelli1, Bhima Bhukya1, 1Department of Clinical Studies, School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA.

Antimicrobial resistance (AR) is a global problem with serious implications for public health. AR genes are prevalent on animal farms but little is known about their origin and distribution patterns in animal farm agroecosystems. In this study, a total of 20 resistomes (collections of AR genes), 5 each from animal feces, manure, near and far soil, on dairy farms were analyzed using shotgun approach. Antimicrobial resistance genes were detected on all 5 farms and only 2% was annotated to AR genes, but varied with sample type (P < 0.05). Despite variations in abundance, majority of AR genes (acrB, bcrA, macB, mdtF, pbp1a, tetL, tetM, tetO, tetQ, tetS, tetW, vanrA, vanrB) that conferred resistance to multiple antibiotics, including macrolides, β-lactams, amphenicols, and tetracyclines, were common to all samples. Additionally, fecal and manure resistomes contained AR genes specific for quinolones, sulfonamides and aminoglycosides. Across all farms, manure was identified as a “Hot Spot” with the greatest abundance and diversity of AR genes. We compared AR genes from present data set with publically available data sets using hierarchal clustering. Multidrug resistant AR genes were prevalent across different animal species and humans, implicating an exchange of AR genes between unrelated microbial niches that may be potentiated by human activities. This study reports the prevalence of AR genes across different farm sectors and identifies potential pathways for horizontal transmission of AR genes (animal-manure-soil) in dairy agroecosystems.

Key Words: antimicrobial resistance, agroecosystems, antimicrobial resistance (AR) genes