Abstract:
Recognizing antibiotic resistance genes as a contaminant and regulating their levels in surface and treated wastewater is imperative for combating the global threat of antimicrobial resistance (AMR). A major roadblock in setting regulatory standards and QMRA for AMR is absence of knowledge on what levels are safe with respect to AMR. This study tracked the rise in AMR (indicated by sul1 gene) in microbial community sourced from Upper Ganga canal (UGC), Roorkee, India (surface water) and drain water (DW), upon exposure to Diclofenac, Triclosan, and Ciprofloxacin. These three drugs are widely used in India as painkiller, antimicrobial in personal care products and as a prescriptive antibiotic respectively. The latter two are known to trigger escalation of AMR, while the former is used in treatment of antibiotic resistant infections. A total of 108 batch reactors were set up for each of the drugs with varying concentrations (0.1 μg/L, 1 μg/L, 5 μg/L, 10 μg/L, and 100 μg/L). These batch reactors were sacrificed in triplicates after 2, 4, 6, 8, 12, 24, and 48 hours and stored at -20C until further processing. In case of both, UGC and DW, the exposure to Diclofenac and Triclosan exacerbated AMR as indicated by the levels of sul1 gene. Levels of sul1 in the microbial community in DW increased about 1.5 order of magnitude upon exposure to Dc, versus 4 orders of increase in the microbial community of UGC, when exposed to Dc. In case of exposure to Triclosan, the DW underwent single order increase in the levels of sul1, relative to 4 orders of magnitude in UGC. This implies that UGC is much more sensitive to AMR proliferation when exposed to Triclosan and Diclofenac.
