Effect of earthworms in removal and fate of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG) during clinical laboratory wastewater treatment by vermifiltration

Abstract

Wastewater treatment plants (WWTPs) effluent has been implicated in the spread of antibiotic resistant bacteria (ARB), and antibiotic resistant genes (ARG) as the WWTP environment contains multiple selective pressures that may increase mutation rates, pathogen survivability, and induce gene transfer between bacteria. In lieu of this, the present study explored the effects and dynamics of earthworm-microorganisms interactions on the treatment efficacy of clinical laboratory wastewater treatment by vermifiltration technology and the effect of earthworms in the fate of removal of pathogens, ARB and ARG. The study is the first of its kind to investigate the performance efficacy of vermifilter (VF) for clinical laboratory wastewater treatment. The results of the study showed that earthworms and VF associated microbial community had a significant effect on BOD and COD reduction (78-85%), coliforms and pathogen removal (>99.9 %) and caused a significant shift in the prevalence pattern of antibiotic resistant bacteria. Additionally, molecular profiling of ESBL, mec-A and colistin gene showed the mechanisms behind the resistance pattern. The microbial community diversity in the influent, earthworms and filter media layers associated with the VF assists in the formation of biofilm, which helps in the removal of pathogens from the wastewater. also results in a paradigm shift in the resistance profile of ARB and ARG, specifically most effective against drugs, targeting cell wall and protein synthesis inhibition such as Ampicillin, Ticarcillin, Gentamicin and Chloramphenicol. These findings further validate vermifiltration technology as a sustainable and natural treatment technology for clinical laboratory wastewater, specifically for the removal of pathogens and antibiotic resistance.