A Survey of Drug Resistance bla Genes Originating from Synthetic Plasmid Vectors in Six Chinese Rivers

Abstract

Antibiotic resistance poses a significant challenge to human health and its rate continues to rise globally. While antibiotic-selectable synthetic plasmid vectors have proved invaluable tools of genetic engineering, this class of artificial recombinant DNA sequences with high expression of antibiotic resistance genes presents an unknown risk beyond the laboratory setting. Contamination of environmental microbes with synthetic plasmid vector-sourced antibiotic resistance genes may represent a yet unrecognized source of antibiotic resistance. In this study, PCR and real-time quantitative PCR were used to investigate the synthetic plasmid vector-originated ampicillin resistance gene, β-lactam antibiotic (blá), in microbes from six Chinese rivers with significant human interactions. Various levels of blá were detected in all six rivers, with the highest levels in the Pearl and Haihe rivers. To validate the blá pollution, environmental plasmids in the river samples were captured by the E. coli transformants from the community plasmid metagenome. The resultant plasmid library of 205 ampicillin-resistant E. coli (transformants) showed a blá-positive rate of 27.3% by PCR. Sequencing results confirmed the synthetic plasmid vector sources. In addition, results of the Kirby-Bauer disc-diffusion test reinforced the ampicillin-resistant functions of the environmental plasmids. The resistance spectrum of transformants from the Pearl and Haihe rivers, in particular, had expanded to the third- and fourth-generation of cephalosporin drugs, while that of other transformants mainly involved first- and second-generation cephalosporins. This study not only reveals environmental contamination of synthetic plasmid vector-sourced blá drug resistance genes in Chinese rivers, but also suggests that synthetic plasmid vectors may represent a source of antibiotic resistance in humans.

The Occurrence of the Colistin Resistance Gene mcr-1 in the Haihe River (China)

“…Methods for the concentration of bacterial cells, were performed as previously described [24]. Briefly, 10 L water samples were filtered through a sterilized steel filter (Millipore, Billerica, MA, U.S.) equipped with a 0.22 μm polycarbonate membrane (100 mm, Millipore, Tokyo, Japan) under 0.15 MPa pressure.…”

Chlorine disinfection increases both intracellular and extracellular antibiotic resistance genes in a full-scale wastewater treatment plant

“…Water samples (10 L) were vacuum-filtered to concentrate the microbial biomass with polytetra fluoroethylene membranes (0.45 µm, Millipore, USA) (Chen et al, 2012).…”

Horizontal Dissemination of Antimicrobial Resistance Determinants in Multiple Salmonella Serotypes following Isolation from the Commercial Swine Operation Environment after Manure Application

“…␤-Lactamase-encoding (bla) genes, including bla TEM and bla CMY , were detected in the plasmids which encoded the resistance to ampicillin and cephalosporin group antimicrobials. Several mechanisms are available for bla genes to support HGT between bacteria, thereby ensuring the spread of these markers to new hosts and the environment (14,55). The heavy use of specific antimicrobials such as tetracycline plays a key role in plasmid dissemination and allows for the selection and enrichment of bacteria with multidrug-resistant plasmids (22,56,57).…”