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Quantification of Tetracycline Resistance Genes in Feedlot Lagoons Using Real-time PCR

Lookup NU author(s): Dr Charles Knapp, Professor David Graham


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A new real-time PCR method is presented that detects and quantifies three tetracycline resistance genes [TcR; tet(O), tet(W), and tet(Q)] in mixed microbial communities resident in feedlot lagoon wastewater. TcR-gene real-time TaqMan primer/probe sets were developed and optimized to quantify the tetracycline resistance genes present in seven different cattle feedlot lagoons to validate the method and to assess whether resistance gene concentrations correlate with free tetracycline levels in lagoon waters. The method proved to be sensitive across a wide range of gene concentrations, and provided consistent and reproducible results from complex lagoon water samples. Total resistance gene concentrations were significantly linearly correlated with free tetracycline levels (r2 = 0.52, p <0.01; n = 19), with resistance concentrations typically being >10-fold greater in lagoon samples with above-median tetracycline levels (>4.8 μg/L using ELISA techniques). The tet(W) and tet(Q) were the more commonly found TcR genes in the lagoon waters of the three genes tested. The successful development of this real-time PCR assay will permit other studies quantifying tetracycline resistance gene numbers in environmental and other samples.

Publication metadata

Author(s): Smith MS, Yang RK, Knapp CW, Niu Y, Peak N, Hanfelt M, Galland JS, Graham DW

Publication type: Article

Publication status: Published

Journal: Applied and Environmental Microbiology

Year: 2004

Volume: 70

Pages: 7372-7377

ISSN (print): 0099-2240

ISSN (electronic): 1098-5336