Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 30, 2008
Publication Date: July 6, 2008
Citation: Callaway, T.R., Rychlik, T.S., Edrington, T.S., Anderson, R.C., Nisbet, D.J. 2008. How are we making bacteria more resistant to antibiotics? Darwinian impacts [abstract]. American Society of Animal Science/American Dairy Science Association Joint Annual Meeting, July 7-11, 2008, Indianapolis, Indiana. Journal of Animal Science. 86(Supplement 2):357. Technical Abstract: This presentation will address the Darwinian selection of genes of antibiotic resistance in food animals. Darwin’s concept of survival of the fittest is as critical when applied to bacteria as it is to animals. Bacteria live in a highly competitive environment that is similar to the macrobiological world with its selective pressures. Neo-Darwinism views genes as selfish and as the ultimate unit of natural selection rather than the host organism. Bacteria carrying antibiotic resistance genes are merely vehicles for ensuring the reproduction and dissemination of these genes. Antibiotic resistance genes can be shared horizontally amongst bacteria of the same or different species through conjugation, transduction, and transformation. Mobile genetic elements (DNA fragments, transposons, phage, and plasmids) are wild cards in the evolution of bacteria and can introduce or combine new genes or groups of genes to bacteria, especially antibiotic resistance genes. The horizontal and vertical movement of these genes is critical to the further dissemination of the genes by ensuring the survival of the bacterial hosts. Addition of selective pressure via feeding antibiotics helps to select for new antibiotic resistance and provides an environmental niche opening for resistant strains to fill and proliferate. Strategies for using new or medically-important antibiotics must be developed and implemented that do not enhance Darwinian and neo-Darwinian selection for antibiotic resistance genes and their host organisms. The antibiotic resistance gene is as critical as the bacteria itself as related to the dissemination of antibiotic resistance throughout the food animal population.