engleski

Level of antibiotic resistance gene contamination as a result of discharge of pharmaceutical effluents

Discharge of effluents from pharmaceutical industries pose a significant public health concern as they could promote spread of antibiotic resistance ; however, effects of such discharges were rarely studied. In our previous studies we have showed that effluents from two Croatian pharmaceutical industries are contaminated with high levels of antibiotics and culturable antibiotic resistant bacteria. We also identified antibiotic resistance genes (ARGs) present in these effluents and sediments at the discharge sites by functional metagenomic approach. In this study, we used quantitative PCR to examine the relative abundance of ARGs (ratio of ARGs/16S rRNA gene) and class 1 integron-integrase gene (intl1) in sediments of receiving water bodies during winter and summer season 2016. In Industry 1 research area (azithromycin production), the relative abundances of intl1 gene and all 4 targeted macrolide-resistance genes (msrE, mphG, mefC and ermB) were significantly increased in river sediments at different locations downstream the discharge site compared with reference upstream location (p <0.05 ; ANOVA) during both seasons. In Industry 2 research area (formulation of veterinary antibiotics), the relative abundances of genes conferring resistance to sulfonamides (sul2), tetracyclines (tetC and tet39), β-lactams (blaOXA1 and blaOXA10) and trimethoprim (dfr14) were enriched in receiving stream sediments as compared with the upstream sediment, but only in the summer samples. Regarding intI gene, no significant differences were observed in relative abundances between upstream and downstream locations neither in winter nor summer samples. Overall, our results show that freshwater sediments impacted by pharmaceutical effluents are an important reservoirs for ARGs, which could potentially be transferred to susceptible pathogens at these sites.

Antibiotic resistance ; Antibiotic resistance genes ; Pharmaceutical effluents ; Sediments

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