Current address: Christina A. Engemann, Tetra Tech EM Inc., 8030 Flint Street, Lenexa, KS 66214, USA.
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Disappearance of oxytetracycline resistance genes in aquatic systems
Article first published online: 17 AUG 2006
DOI: 10.1111/j.1574-6968.2006.00419.x
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How to Cite
Engemann, C. A., Adams, L., Knapp, C. W. and Graham, D. W. (2006), Disappearance of oxytetracycline resistance genes in aquatic systems. FEMS Microbiology Letters, 263: 176–182. doi: 10.1111/j.1574-6968.2006.00419.x
Editor: Stefan Schwarz
Publication History
- Issue published online: 22 AUG 2006
- Article first published online: 17 AUG 2006
- Received 10 April 2006; revised 07 July 2006; accepted 10 July 2006.First published online 17 August 2006.
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Keywords:
- antibiotic resistance;
- oxytetracycline;
- real-time PCR;
- gene disappearance kinetics;
- aquatic systems
Abstract
The disappearance of selected tetracycline resistance genes was investigated in different simulated receiving waters to determine conditions that maximize resistance gene loss after release. Wastewater from an operating cattle feedlot lagoon was provided to four pairs of duplicate 3-L flasks, and tet(O), tet(W), tet(M), tet(Q), and 16S rRNA gene levels were monitored over 29 days using real-time PCR. Treatments included simulated sunlight with 0, 25, and 250 μg L−1 nominal oxytetracycline (OTC) levels, respectively, and ‘dark’ conditions. Gene disappearance rates were always highest when light was present, regardless of OTC level. First-order loss coefficients (kd) for the sum of resistance genes were 0.84, 0.75, and 0.81 day−1 for 0.0, 25, and 250 μg L−1 OTC treatments over the first 7 days after release, respectively, whereas kd was 0.49 day−1 under dark conditions, which is significantly lower (P<0.10). kd varied fourfold among the four individual genes, although disappearance patterns were similar among genes. Results suggest that light exposure should be maximized in receiving waters in order to maximize resistance gene loss rate after release.