Evaluation of Macrolide-Lincosamide-Streptogramin B Antimicrobial Resistance at Swine Farms
Zhou, Zhi
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Permalink
https://hdl.handle.net/2142/83351
Description
Title
Evaluation of Macrolide-Lincosamide-Streptogramin B Antimicrobial Resistance at Swine Farms
Author(s)
Zhou, Zhi
Issue Date
2007
Doctoral Committee Chair(s)
Zilles, Julie L.
Department of Study
Civl and Environmental Engineering
Discipline
Civl and Environmental Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Soil Science
Language
eng
Abstract
Antimicrobial use in animal agriculture contributes to increased levels of antimicrobial resistance in the environment. To better evaluate this concern, the levels of macrolide-lincosamide-streptogramin B (MLSB) antimicrobial resistance at swine farms were quantified. A variation of fluorescence in situ hybridization (FISH) was developed to detect the methylation of a specific adenine residue (A2058 in Escherichia coli) in the 23S rRNA responsible for MLSB resistance. A robust and automated image analysis method was then developed to quantify FISH signals. The combination of this FISH method with phylogenetic identification protocols allows the quantification of resistance in particular organisms or groups of organisms. Using this FISH method, a high level of MLSB resistance was confirmed in swine waste samples from an organic farm despite the absence of obvious anthropogenic selective pressures of MLSB antimicrobials and the low level of MLSB resistance observed with culture based methods targeting fecal streptococci. Furthermore, tetracyclines were detected in the swine waste samples, suggesting that selective pressure from tetracyclines may result in MLSB resistance. Clostridium spp. were identified as a dominant population contributing to the high level of MLSB resistance at the organic farm. The different levels of MLS B resistance observed in fecal streptococci and the total microbial community indicate the need for caution in the extrapolation of resistance measurements between organisms. The levels of MLSB antimicrobials and antimicrobial resistance were quantified in manure amended field soils and in soil batch tests, since land application of swine manure has also been proposed as a possible factor in the environmental development and dissemination of antimicrobial resistance; the levels of MLSB antimicrobials in field soils amended with swine manure indicated the persistence of lincomycin and tetracyclines. No significant difference in MLSB resistance was observed between amended and unamended soils, either in the field soils or in laboratory batch tests. These data suggest that land application of swine manure is not causing a long-term increase in the level of MLS B resistant bacteria in the receiving soils.
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