Antibiotic resistance is a serious problem that threatens public health. Bacteria have been shown to transfer antibiotic resistance genes via horizontal gene transfer. Resistance in bacteria has been known to arise from exposure to antibiotics, but recent literature has shown that antimicrobials (such as triclosan and triclocarban) used for personal hygiene and sanitation may also have an active role in the proliferation of resistance to clinically important antibiotics. Given that antimicrobials accumulate in wastewater treatment, antimicrobials in these treatment systems could potentially have a significant impact on antibiotic resistance in the environment. The central hypothesis guiding this research is that household antimicrobials are a selective pressure for antibiotic resistance in anaerobic digestion. The role of antimicrobials on the proliferation of antibiotic resistance in anaerobic digesters will be investigated in this study.  Methanogenesis inhibitory levels of triclosan and triclocarban will be defined for municipal anaerobic biomass from South Shore Wastewater Reclamation Facility (Milwaukee, WI, USA). Bench-scale anaerobic reactors will be gradually spiked (slow ramp to final concentration) or immediately spiked (no ramp to final concentration) with three sub-inhibitory levels of each antimicrobial. Steady-state methane production and volatile fatty acid levels will be quantified under the various antimicrobial loading conditions to assess reactor functional health. Select antibiotic resistance genes and genes associated with gene transfer (intI1) will be quantified via qPCR before and after perturbation with antimicrobials. Given that cross-resistance and co-resistance to antibiotics may arise with resistance to antimicrobials, it is expected that the concentration of antibiotic resistance genes will increase.

Role of triclocarban and triclosan on the functional health and proliferation of antibiotic resistance genes in anaerobic digestion

248th National Meeting (2014)

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