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Quantifying Attachment and Antibiotic Resistance of Escherichia coli from Conventional and Organic Swine Manure
Author(s) -
Zwonitzer Martha R.,
Soupir Michelle L.,
Jarboe Laura R.,
Smith Douglas R.
Publication year - 2016
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2015.05.0245
Subject(s) - antibiotics , tylosin , manure , antibiotic resistance , microbiology and biotechnology , tetracycline , escherichia coli , neomycin , bacteria , chlortetracycline , biology , streptomycin , ampicillin , amoxicillin , kanamycin , erythromycin , agronomy , biochemistry , gene , genetics
Broad‐spectrum antibiotics are often administered to swine, contributing to the occurrence of antibiotic‐resistant bacteria in their manure. During land application, the bacteria in swine manure preferentially attach to particles in the soil, affecting their transport in overland flow. However, a quantitative understanding of these attachment mechanisms is lacking, and their relationship to antibiotic resistance is unknown. The objective of this study is to examine the relationships between antibiotic resistance and attachment to very fine silica sand in Escherichia coli collected from swine manure. A total of 556 isolates were collected from six farms, two organic and four conventional (antibiotics fed prophylactically). Antibiotic resistance was quantified using 13 antibiotics at three minimum inhibitory concentrations: resistant, intermediate, and susceptible. Of the 556 isolates used in the antibiotic resistance assays, 491 were subjected to an attachment assay. Results show that E. coli isolates from conventional systems were significantly more resistant to amoxicillin, ampicillin, chlortetracycline, erythromycin, kanamycin, neomycin, streptomycin, tetracycline, and tylosin ( P < 0.001). Results also indicate that E. coli isolated from conventional systems attached to very fine silica sand at significantly higher levels than those from organic systems ( P < 0.001). Statistical analysis showed that a significant relationship did not exist between antibiotic resistance levels and attachment in E. coli from conventional systems but did for organic systems ( P < 0.001). Better quantification of these relationships is critical to understanding the behavior of E. coli in the environment and preventing exposure of human populations to antibiotic‐resistant bacteria. Core Ideas Greater levels of attachment were found in E. coli from conventional swine systems. A significant relationship exists between resistance and attachment for organic swine systems. Greater resistance to 9 of 13 antibiotics was found in conventional swine system E. coli .