Analysis of wastewater contamination to assess contributions to antimicrobial resistance with proposed algal solution

Importance of analysing antibiotic and heavy metal contamination in wastewater to monitor contributions towards antimicrobial resistance in aquatic life
Deborah Reid

Reid, Deborah¹., Escudero, Ania¹., Spencer, Janice². and Hunter, Colin¹.

¹ Department of Civil Engineering and Environmental Management, Glasgow Caledonian University, ² Department of Biological and Biomedical Sciences, Glasgow Caledonian University

Theme: Importance of a global wastewater surveillance system for public health

Background - Water borne pollutants are a known link to increasing levels of antimicrobial resistance (AMR) in aquatic life. An important route for AMR into the marine environment is via sewerage networks where potential key control points are located in wastewater treatment plants (WWTPs) ¹. Presently there is no mainstream strategy to influence the emerging persistent antibiotic and heavy metal contamination linking resistance gene contamination in wastewater (WW) and WWTP biofilms to the aquatic environment.

Methods- Qualitative and quantitative analysis of WW and WWTP biofilms from four different sampling points (in triplicate) throughout the WWTP over a yearlong sampling campaign. Flame Atomic Absorption Spectrophotometry (FAAS) for heavy metal (HM) quantification (Cr, Cu, Fe, Pb, Mg, Mn, Ni, Ag and Zn). High-Pressure Liquid Chromatography Mass Spectrometry/MS (HPLC-MS/MS) for antibiotic detection and quantification (amoxicillin, azithromycin, ciprofloxacin, clarithromycin, erythromycin, flucloxacillin, metronidazole, ofloxacin, sulfamethoxazole and trimethoprim). High-Throughput real-time chip PCR (qPCR) for quantification of AMR genes (qepA, sul1_2, blandM, blaCTX-M, blaTEM_1, tetX, mcr1, nimE, ermF_1, acc(6’)-Ib_2 and dfrA1_1).

Results- A detection was made of significant seasonal variations of pharmaceuticals and heavy metals in conjunction with the identification of associated AMR genes in wastewater and biofilms. Several of the antibiotics were detected over the predicted no-effect concentration (PNEC)² in both the wastewater and in the biofilms with one producing a bio-concentration factor of 3.1, which classifies it (according to EU guidelines) as bio-accumulative in the WWTP. This accumulation may be significantly influencing which resistance genes transfer into the receiving environmental waters and aquatic life.

Conclusion and Future Work- The bioaccumulation of heavy metals and antibiotics by wastewater biofilms may influence the quantity of resistance genes found in the surrounding aquatic environment.
This research will guide wastewater management to reduce AMR. It will also provide concentrations for the next stage of this study into the phycoremediation of antibiotics and heavy metals using the micro-algae Chlamydomonas acidophila. A photo-bioreactor culturing these algae in WW may reduce the bioavailability of antibiotics and heavy metals throughout the WWTP and reduce AMR in the aquatic environment.

References- ¹ROBERTS, P.H. & THOMAS, K.V., 2006. The occurrence of selected pharmaceuticals in wastewater effluent and surface waters of the lower Tyne catchment. Science of the Total Environment. 356(1), pp.143-153.
²BENGTSSON-PALME, J. & LARSSON, D.J., 2016. Concentrations of antibiotics predicted to select for resistant bacteria: proposed limits for environmental regulation. Environment International. 86, pp.140-149.