Overexpression of antibiotic resistance genes in hospital effluents over time.
Effluents contain a diverse abundance of antibiotic resistance genes that augment the resistome of receiving aquatic environments. However, uncertainty remains regarding their temporal persistence, transcription and response to anthropogenic factors, such as antibiotic usage. We present a spatiotemporal study within a river catchment (River Cam, UK) that aims to determine the contribution of antibiotic resistance gene-containing effluents originating from sites of varying antibiotic usage to the receiving environment.



Gene abundance in effluents (municipal hospital and dairy farm) was compared against background samples of the receiving aquatic environment (i.e. the catchment source) to determine the resistome contribution of effluents. We used metagenomics and metatranscriptomics to correlate DNA and RNA abundance and identified differentially regulated gene transcripts.



We found that mean antibiotic resistance gene and transcript abundances were correlated for both hospital ( ρ  = 0.9, two-tailed P  <0.0001) and farm ( ρ  = 0.5, two-tailed P   <0.0001) effluents and that two β-lactam resistance genes ( bla GES and bla OXA ) were overexpressed in all hospital effluent samples. High β-lactam resistance gene transcript abundance was related to hospital antibiotic usage over time and hospital effluents contained antibiotic residues.



We conclude that effluents contribute high levels of antibiotic resistance genes to the aquatic environment; these genes are expressed at significant levels and are possibly related to the level of antibiotic usage at the effluent source.
Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.|Institute of Integrative Biology, University of Liverpool, Liverpool, UK.
Will P M
WPM
Rowe
Centre for Environment, Fisheries and Aquaculture Science, Weymouth, UK.
Craig
C
Baker-Austin
Centre for Environment, Fisheries and Aquaculture Science, Weymouth, UK.
David W
DW
Verner-Jeffreys
Environment, Health and Safety, GlaxoSmithKline, Ware, UK.
Jim J
JJ
Ryan
Pharmacy Department, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
Christianne
C
Micallef
Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
Duncan J
DJ
Maskell
Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
Gareth P
GP
Pearce
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000235:genetics; D003612:Dairying; D004352:Drug Resistance, Microbial / Q000235:genetics*; D000072480:Farms; D015870:Gene Expression; D020869:Gene Expression Profiling; D005798:Genes, Bacterial; D006761:Hospitals; D006801:Humans; D056186:Metagenomics; D045483:Rivers / Q000382:microbiology; D062211:Spatio-Temporal Analysis; D062065:Wastewater / Q000382:microbiology*; D014871:Water Microbiology; D018440:beta-Lactam Resistance / Q000235:genetics
D000900:Anti-Bacterial Agents; D062065:Wastewater