Occurrence of tetracycline resistance genes in aquaculture facilities with varying use of oxytetracycline.
ABSTRACT The contribution of human activities to environmental reservoirs of antibiotic resistance is poorly understood. The purpose of this study was to determine if oxytetracycline (OTC) use in aquaculture facilities increased the detection frequency (i.e., prevalence) of tetracycline resistance (tet(R)) genes relative to facilities with no recent OTC treatment. We used polymerase chain reaction to screen water and sediment from four noncommercial fish farms in northwestern Wisconsin for the presence of ten tet(R) determinants: tet(A), tet(B), tet(D), tet(E), tet(G), tet(M), tet(O), tet(Q), tet(S), and tet(W). Water from farms with recent OTC use had significantly higher tet(R) detection frequencies than did water from farms without recent OTC use, with prevalence in raceways and rearing ponds of farms with recent OTC use exceeding by more than twofold that of farms not using OTC. Effluent from all farms, regardless of treatment regime, had higher tet(R) detection frequencies than their corresponding influent for all genes, but the specific combinations of tet(R) genes detected in a sample were not different from their corresponding influent. Although OTC use was associated with the increased occurrence and diversity of tet(R) genes in water samples, it was not found to relate to tet(R) gene occurrence in sediment samples. Sediment samples from facilities with no recent OTC use had significantly higher frequencies of tet(R) gene detection than did samples from facilities with recent OTC use. All of the tet(R) genes were detected in both the medicated and nonmedicated feed samples analyzed in this study. These findings suggest that both OTC treatment in aquaculture facilities and the farms themselves may be sources of tet(R) gene introduction to the environment. To our knowledge, this is the first study to use genotypic and cultivation-independent methods to examine tet(R) gene occurrence associated with OTC use in aquaculture.
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ABSTRACT: AIMS: The objective of this study was to determine if varying levels of urbanization influence the dominant bacterial species of mildly resistant (0.03 mmol l(-1) tetracycline) and highly resistant (0.06 mmol l(-1) tetracycline) bacteria in sediment and water. Also the level of urbanization was further evaluated to determine if the diversity of tetracycline resistance genes present in the isolates and the capability of transferring their resistance were influenced. METHODS AND RESULTS: Sediment and water samples collected from five sampling sites were plated in triplicate on nutrient agar plates with a mild dose (0.03mmol l(-1) tetracycline) and a highly dose (0.06 mmol l(-1) tetracycline) of tetracycline. Five colonies from each plate plus an additional five from each triplicate group were randomly selected and isolated on nutrient agar containing 0.03mmol l(-1) tetracycline (400 isolates). The isolates were identified by 16S rRNA gene sequencing and comparison to GenBank using BLAST. The isolates were also screened for 15 tetracycline resistance genes using a multiplex PCR assay and their ability to transfer resistance through conjugation experiments using a kanamycin-resistant E. coli K-12 strain labeled with a green fluorescent protein gene. Results from this study indicate that the dominant resistant organisms in this watershed are Acinetobacter spp., Chyrseobacterium spp., Serratia spp., Pseudomonas spp., Aeromonas spp., and E. coli. All of these organisms are Gram-negative and are closely related to pathogenic species. A majority of the isolates (66%) were capable of transferring their resistance, and there was a greater incidence of tet resistance transfer with increasing urbanization. Also it was determined that the dominant resistance genes in the watershed are tet(W) and tet(A). SIGNIFICANCE AND IMPACT OF STUDY: These results indicate that urbanization influences occurrence of tetracycline-resistant bacteria and the potential for transfer of resistance genes. This article is protected by copyright. All rights reserved.Journal of Applied Microbiology 06/2013; · 2.20 Impact Factor
Dataset: ABB 2013032910352278 (2)
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ABSTRACT: Presently, many pharmaceuticals are listed as emerging contaminants since they are considered to be great potential threats to environmental ecosystems. These contaminants, thus, present significant research interest due to their extensive use and their physicochemical and toxicological properties. This review discusses a whole range of findings that address various aspects of the usage, occurrence, and potentially environmental risks of pharmaceuticals released from various anthropogenic sources, with emphasis on the aquatic systems in Vietnam. The published information and collected data on the usage and occurrence of antibiotics and synthetic hormone in effluents and aquatic systems of Vietnam is reported. This is followed by a potential ecological risk assessment of these pollutants. The extensive use of antibiotics and synthetic hormones in Vietnam could cause the discharge and accumulation of these contaminants in the aquatic systems and potentially poses serious risks for ecosystems. Vietnam is known to have extensively used antibiotics and synthetic hormones, so these contaminants are inevitably detected in aquatic systems. Thus, an appropriate monitoring program of these contaminants is urgently needed in order to mitigate their negative effects and protect the ecosystems.Environmental Science and Pollution Research 08/2013; · 2.62 Impact Factor