Preliminary assessment of antimicrobial activity and acute toxicity of norfloxacin chlorination by-product mixture.

Among drugs and personal care products, antibiotics arouse interest since they are widely used in human and veterinary medicine and can lead to the development of bacterial resistance. Usually, sewage treatment does not remove most of these compounds. So, these drugs can reach water treatment plants (WTP), where disinfection with chlorine compounds is common. This work aimed to evaluate the antimicrobial activity and preliminary toxicity of the mix of by-products forming due to the chlorination of norfloxacin. This is a fluoroquinolone antibiotic indicated for the treatment of urinary infection and gonorrhea, with sodium hypochlorite (NaClO). The drug was subjected to chlorination tests, on a bench scale, with several reaction times (from 5 min to 24 h). Analyses of high-resolution mass spectrometry (MS) were performed for the characterization of the by-products. The MS results showed five peaks attributed to the by-products' formation, of which four were identified. The antibiogram results indicated that the solution that contained the mixture of the by-products lost antibacterial activity against the E. coli strain studied. The acute toxicity tests for the Artemia salina microcrustacean showed that the blend of the by-products exhibited higher toxicity than pure norfloxacin.