Antibiotic resistance in bacteria causing disease is an ever growing threat to the world. Recently, environmental bacteria have become established as important both as sources of antibiotic resistance genes and in disseminating resistance genes. Low levels of antibiotics and other pharmaceuticals are regularly released into water environments via wastewater, and the concern is that such environmental contamination may serve to create hotspots for antibiotic resistance gene selection and dissemination. In this study, microcosms were created from water and sediments gathered from a lake in Sweden only lightly affected by human activities. The microcosms were exposed to a mixture of antibiotics of varying environmentally relevant concentrations (i.e., concentrations commonly encountered in wastewaters) in order to investigate the effect of low levels of antibiotics on antibiotic resistance gene abundances and dynamics in a previously uncontaminated environment. Antibiotic concentrations were measured using liquid chromatography-tandem mass spectrometry. Abundances of seven antibiotic resistance genes and the class 1 integron integrase gene, intI1, were quantified using real-time PCR. Resistance genes sulI and ermB were quantified in the microcosm sediments with mean abundances 5 and 15 gene copies/106 16S rRNA gene copies, respectively. Class 1 integrons were determined in the sediments with a mean concentration of 3.8×104 copies/106 16S rRNA gene copies. The antibiotic treatment had no observable effect on antibiotic resistance gene or integron abundances.
Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden;Department of Chemistry, Umeå University, Umeå, Sweden;Department of Chemistry, Umeå University, Umeå, Sweden;Department of Chemistry, Umeå University, Umeå, Sweden;Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden;Department of Microbiology, Medical Services, County Hospital Ryhov, Jönköping, Sweden
Recommended Citation:
Björn Berglund,Ghazanfar Ali Khan,Richard Lindberg,et al. Abundance and Dynamics of Antibiotic Resistance Genes and Integrons in Lake Sediment Microcosms[J]. PLOS ONE,2014-01-01,9(9)