title: Broad dissemination of plasmid-mediated quinolone resistance genes in sediments of two urban coastal wetlands.
abstract: Contamination of soil and water with antibiotic-resistant bacteria may create reservoirs of antibiotic resistance genes that have the potential to negatively impact future public health through horizontal gene transfer. The plasmid-mediated quinolone resistance genes qnrA, qnrB, qnrS, qepA, and aac(6')-Ib-cr were detected by PCR amplification of metagenomic DNA from surface sediments of the Tijuana River Estuary, a sewage-impacted coastal wetland along the U.S.-Mexico border; sediments of Famosa Slough, a nearby urban wetland that is largely unaffected by sewage, contained only qnrB, qnrS, and qepA. The number of PCR-positive sites and replicates increased in both wetlands after rainfall. Real-time quantitative PCR revealed a significant increase (p < 0.0005) in qnrA abundance (copies per gram sediment or per 16S rDNA copy) in Tijuana River Estuary sediments immediately following rainfall, but no significant change was measured at Famosa Slough (p > 0.1). Nucleotide sequences of cloned qnrA amplicons were all affiliated with qnrA genes found on plasmids of clinical isolates with one exception that was most similar to the chromosomal qnrA gene found in Shewanella algae. Our results suggest that urban wetlands may become reservoirs of antibiotic resistance genes, particularly where wastewater is improperly managed.
authors.affiliation: Department of Biology, Point Loma Nazarene University, San Diego, California 92106, USA. davidcummings@pointloma.edu
authors.forename: David E
authors.initials: DE
authors.lastname: Cummings
authors.forename: Karisa F
authors.initials: KF
authors.lastname: Archer
authors.forename: David J
authors.initials: DJ
authors.lastname: Arriola
authors.forename: Pieter A
authors.initials: PA
authors.lastname: Baker
authors.forename: K Grace
authors.initials: KG
authors.lastname: Faucett
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Laroya
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Pfeil
authors.forename: Cody R
authors.initials: CR
authors.lastname: Ryan
authors.forename: Kelsey R U
authors.initials: KR
authors.lastname: Ryan
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Zuill
mesh_terms: D000890:Anti-Infective Agents / Q000032:analysis* / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002947:Cities; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004784:Environmental Monitoring / Q000379:methods; D005798:Genes, Bacterial; D019015:Geologic Sediments / Q000737:chemistry* / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D015363:Quinolones / Q000032:analysis* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism; D053833:Wetlands
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D015363:Quinolones; D014874:Water Pollutants, Chemical