|Chee Sanford, Joanne|
Submitted to: Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2009
Publication Date: 4/1/2010
Citation: Koike, S., Aminov, R.I., Yannarell, A.C., Gans, H.D., Krapac, I.G., Chee Sanford, J.C., Mackie, R.I. 2010. Molecular Ecology of Macrolide-Lincosamide-Streptogramin B Methylases in Waste Lagoons and Subsurface Waters Associated with Swine Production. Microbial Ecology. 59(3):487-498. Interpretive Summary: The entry of antibiotics and antibiotic-resistant bacteria into soil and groundwater environments via animal waste contamination has raised issues over the persistence of antibiotic resistance genes in natural environments. The mobilization of these genes into terrestrial systems such as agricultural fields has also raised questions of how these genetic traits affect the natural function of resident soil microorganisms. Tylosin is the the chemical analog to the antibiotic erythromycin, and is exclusively used in swine production in this country. In this study, the genes conferring resistance to erythromycin was detected more frequently than the genes specific for tylosin resistance. The significance of the results indicate that environments can serve as a reservoir that allows for both selection of new genes and maintenance of co-selected genes.
Technical Abstract: RNA methylase genes are common antibiotic resistance determinants for multiple drugs of the macrolide, lincosamide, and streptogramin B (MLSB) families. We used molecular methods to investigate the diversity, distribution, and abundance of MLSB methylases in waste lagoons and groundwater wells at two swine farms with a history of tylosin (a macrolide antibiotic structurally related to erythromycin) and tetracycline usage. Phylogenetic analysis guided primer design for quantification of MLSB resistance genes found in tylosin-producing Streptomyces (tlr(B), tlr(D)) and commensal/pathogenic bacteria (erm(A), erm(B), erm(C), erm(F), erm(G), erm(Q)). The near absence of tlr genes at these sites suggested a lack of native antibiotic-producing organisms. The gene combination erm(ABCF) was found in all lagoon samples analyzed. These four genes were also detected with high frequency in wells previously found to be contaminated by lagoon leakage. A weak correlation was found between the distribution of erm genes and previously reported patterns of tetracycline resistance determinants, suggesting that dissemination of these genes into the environment is not necessarily linked. Considerations of gene origins in history (i.e., phylogeny) and gene distributions in the landscape provide a useful “molecular ecology” framework for studying environmental spread of antibiotic resistance.