Effect of antibiotics and antibiotic by-products on the chlorine resistance of biofilms in drinking water distribution systems

This study investigated the effects of tetracycline (TC) and sulfadiazine (SD), along with their degradation products, on biofilm chlorine resistance. The results showed that low concentrations of antibiotics and their degradation products promoted biofilm formation on tube surfaces and increased resistance to chlorine. There was a positive correlation between antibiotic levels, degradation products, and biofilm chlorine resistance within a specific concentration range. SD had a more significant impact on biofilm chlorine resistance compared to TC. The presence of both antibiotics and their degradation products in water led to an increase in biofilm chlorine resistance, especially when combined with 0.3 mg/L sodium hypochlorite. The study shows a positive association between antibiotic and degradation product concentrations and the biofilms' improved chlorine resistance, a phenomenon that could have major consequences for water treatment efforts. Additionally, higher concentrations of antibiotics and their degradation products were associated with reduced biodiversity within the biofilm. Overall, the findings suggest that the presence of antibiotics and their degradation products can influence biofilm formation, alter bacterial species composition, and enhance biofilm resistance to chlorine in drinking water distribution systems. This fresh perspective on the relationship between pharmaceutical residues and microbial communities in water systems could transform our approach to assuring water safety and combatting antimicrobial resistance.