ARS | Publication request: Microbial Ecology of and Antimicrobial Resistance in Stored Swine Manure

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 3, 2009
Publication Date: N/A

Technical Abstract: Antimicrobial compounds such as tylosin have been commonly used as feed additives for domestic animals to reduce infection and promote growth. Recent reports have suggested such feeding practices may result in increased microbial resistance to antibiotics, which can have an impact on human health. While many investigations have centered on antibiotic resistance in coliforms and other aerobic bacteria, less attention has been directed towards investigating antibiotic resistance in the anaerobic microflora found in the feces and stored manure of domestic animals which may serve as reservoirs of antibiotic resistance genes. Our laboratory has been studying the predominant bacterial populations present in both pig feces and manure storage pits in relation to odor production. Results of pure culture isolation and direct 16S rDNA sequence analyses indicate that the primary bacterial populations of the swine feces and manure storage pits are anaerobic, low G+C, Gram-positive bacteria, most of which represent novel genera and species. As part of this study, we investigated the potential antibiotic resistance in the anaerobic bacterial populations present in these ecosystems. Pure cultures were isolated following plating on media containing various antibiotics, as well as polymerase chain reaction (PCR) analyses of total deoxyribonucleic acid (DNA) using primers based on a variety of antibiotic resistance genes. Results of these studies indicate that both the swine gastrointestinal (GI) tract and stored manure may serve as reservoirs of known and novel antibiotic resistance bacteria and genes.