Ceppi batterici antibiotico-resistenti : presenza ed abbattimento in impianti di depurazione di acque reflue urbane

Antibiotic-resistance bacteria (ARB)are ubiquitous, finding them in treated and non treated wastewater, superficial and groundwater increasing the risk for human health. The aim of this study is to verify ARB presence in 2 wastewater treatment focusing on the effect of treatment processes plants (WWTPs)in Milan city that have been considered, since wastewater contain antibiotic and their by-products in concentration from ng/L to μg/L. Sample were collected at input (IN BIO) and output (OUT BIO) of the biological reactor and after UV disinfection (plant 1) and peracetic acid (PAA) (plant 2). The potential antibiotic-resistance in E. coli was tested at three different concentration (8, 16, 32 mg/L) towards four compounds: ampicillin, tetracycline, chloramphenicol and erythromycin. The result show resistance of E. coli to ampicillin and chloramphenicol and no resistance to tetracycline in both the WWTPs. Nevertheless, while no change in the resistance to ampicillin (20-40%)was observed in plant 1, a significant decrease (from 50-50% to 20-30%) was observed after biological reactor in plant 2. The resistance to chloramphenicol was found in a range of 1-13% in both the plants.