Distribution and characterization of ampicillin- and tetracycline-resistant <it>Escherichia coli </it>from feedlot cattle fed subtherapeutic antimicrobials
<p>Abstract</p> <p>Background</p> <p>Feedlot cattle in North America are routinely fed subtherapeutic levels of antimicrobials to prevent disease and improve the efficiency of growth. This practice has been shown to promote antimicrobial resistance (AMR) in subpopulatio...
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| Format: | Article |
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BMC
2011-04-01
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| Series: | BMC Microbiology |
| Online Access: | http://www.biomedcentral.com/1471-2180/11/78 |
| _version_ | 1811330063542517760 |
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| author | Yanke L Jay Sharma Ranjana Louie Marie Mirzaagha Parasto Topp Ed McAllister Tim A |
| author_facet | Yanke L Jay Sharma Ranjana Louie Marie Mirzaagha Parasto Topp Ed McAllister Tim A |
| author_sort | Yanke L Jay |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Feedlot cattle in North America are routinely fed subtherapeutic levels of antimicrobials to prevent disease and improve the efficiency of growth. This practice has been shown to promote antimicrobial resistance (AMR) in subpopulations of intestinal microflora including <it>Escherichia coli</it>. To date, studies of AMR in feedlot production settings have rarely employed selective isolation, therefore yielding too few AMR isolates to enable characterization of the emergence and nature of AMR in <it>E. coli </it>as an indicator bacterium. <it>E. coli </it>isolates (<it>n </it>= 531) were recovered from 140 cattle that were housed (10 animals/pen) in 14 pens and received no dietary antimicrobials (control - 5 pens, CON), or were intermittently administered subtherapeutic levels of chlortetracycline (5 pens-T), chlortetracycline + sulfamethazine (4 pens-TS), or virginiamycin (5 pens-V) for two separate periods over a 9-month feeding period. Phenotype and genotype of the isolates were determined by susceptibility testing and pulsed field gel electrophoresis and distribution of characterized isolates among housed cattle reported. It was hypothesized that the feeding of subtherapeutic antibiotics would increase the isolation of distinct genotypes of AMR <it>E. coli </it>from cattle.</p> <p>Results</p> <p>Overall, patterns of antimicrobial resistance expressed by <it>E. coli </it>isolates did not change among diet groups (CON vs. antibiotic treatments), however; isolates obtained on selective plates (i.e., M<sup>A</sup>,M<sup>T</sup>), exhibited multi-resistance to sulfamethoxazole and chloramphenicol more frequently when obtained from TS-fed steers than from other treatments. Antibiograms and PFGE patterns suggested that AMR <it>E. coli </it>were readily transferred among steers within pens. Most M<sup>T </sup>isolates possessed the <it>tet</it>(B) efflux gene (58.2, 53.5, 40.8, and 50.6% of isolates from CON, T, TS, and V steers, respectively) whereas among the M<sup>A </sup>(ampicillin-resistant) isolates, the <it>tem1</it>-like determinant was predominant (occurring in 50, 66.7, 80.3, and 100% of isolates from CON, T, TS, and V steers, respectively).</p> <p>Conclusions</p> <p>Factors other than, or in addition to subtherapeutic administration of antibiotics influence the establishment and transmission of AMR <it>E. coli </it>among feedlot cattle.</p> |
| first_indexed | 2024-04-13T15:54:56Z |
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| institution | Directory Open Access Journal |
| issn | 1471-2180 |
| language | English |
| last_indexed | 2024-04-13T15:54:56Z |
| publishDate | 2011-04-01 |
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| spelling | doaj.art-25d68e9fc5c249859b07167f560a53792022-12-22T02:40:43ZengBMCBMC Microbiology1471-21802011-04-011117810.1186/1471-2180-11-78Distribution and characterization of ampicillin- and tetracycline-resistant <it>Escherichia coli </it>from feedlot cattle fed subtherapeutic antimicrobialsYanke L JaySharma RanjanaLouie MarieMirzaagha ParastoTopp EdMcAllister Tim A<p>Abstract</p> <p>Background</p> <p>Feedlot cattle in North America are routinely fed subtherapeutic levels of antimicrobials to prevent disease and improve the efficiency of growth. This practice has been shown to promote antimicrobial resistance (AMR) in subpopulations of intestinal microflora including <it>Escherichia coli</it>. To date, studies of AMR in feedlot production settings have rarely employed selective isolation, therefore yielding too few AMR isolates to enable characterization of the emergence and nature of AMR in <it>E. coli </it>as an indicator bacterium. <it>E. coli </it>isolates (<it>n </it>= 531) were recovered from 140 cattle that were housed (10 animals/pen) in 14 pens and received no dietary antimicrobials (control - 5 pens, CON), or were intermittently administered subtherapeutic levels of chlortetracycline (5 pens-T), chlortetracycline + sulfamethazine (4 pens-TS), or virginiamycin (5 pens-V) for two separate periods over a 9-month feeding period. Phenotype and genotype of the isolates were determined by susceptibility testing and pulsed field gel electrophoresis and distribution of characterized isolates among housed cattle reported. It was hypothesized that the feeding of subtherapeutic antibiotics would increase the isolation of distinct genotypes of AMR <it>E. coli </it>from cattle.</p> <p>Results</p> <p>Overall, patterns of antimicrobial resistance expressed by <it>E. coli </it>isolates did not change among diet groups (CON vs. antibiotic treatments), however; isolates obtained on selective plates (i.e., M<sup>A</sup>,M<sup>T</sup>), exhibited multi-resistance to sulfamethoxazole and chloramphenicol more frequently when obtained from TS-fed steers than from other treatments. Antibiograms and PFGE patterns suggested that AMR <it>E. coli </it>were readily transferred among steers within pens. Most M<sup>T </sup>isolates possessed the <it>tet</it>(B) efflux gene (58.2, 53.5, 40.8, and 50.6% of isolates from CON, T, TS, and V steers, respectively) whereas among the M<sup>A </sup>(ampicillin-resistant) isolates, the <it>tem1</it>-like determinant was predominant (occurring in 50, 66.7, 80.3, and 100% of isolates from CON, T, TS, and V steers, respectively).</p> <p>Conclusions</p> <p>Factors other than, or in addition to subtherapeutic administration of antibiotics influence the establishment and transmission of AMR <it>E. coli </it>among feedlot cattle.</p>http://www.biomedcentral.com/1471-2180/11/78 |
| spellingShingle | Yanke L Jay Sharma Ranjana Louie Marie Mirzaagha Parasto Topp Ed McAllister Tim A Distribution and characterization of ampicillin- and tetracycline-resistant <it>Escherichia coli </it>from feedlot cattle fed subtherapeutic antimicrobials BMC Microbiology |
| title | Distribution and characterization of ampicillin- and tetracycline-resistant <it>Escherichia coli </it>from feedlot cattle fed subtherapeutic antimicrobials |
| title_full | Distribution and characterization of ampicillin- and tetracycline-resistant <it>Escherichia coli </it>from feedlot cattle fed subtherapeutic antimicrobials |
| title_fullStr | Distribution and characterization of ampicillin- and tetracycline-resistant <it>Escherichia coli </it>from feedlot cattle fed subtherapeutic antimicrobials |
| title_full_unstemmed | Distribution and characterization of ampicillin- and tetracycline-resistant <it>Escherichia coli </it>from feedlot cattle fed subtherapeutic antimicrobials |
| title_short | Distribution and characterization of ampicillin- and tetracycline-resistant <it>Escherichia coli </it>from feedlot cattle fed subtherapeutic antimicrobials |
| title_sort | distribution and characterization of ampicillin and tetracycline resistant it escherichia coli it from feedlot cattle fed subtherapeutic antimicrobials |
| url | http://www.biomedcentral.com/1471-2180/11/78 |
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