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Antimicrobial activity against Gram-positive and Gram-negative bacteria during gatifloxacin degradation by hydroxyl radicals

Caianelo, Marlon, Rodrigues-Silva, Caio, Maniero, Milena Guedes, Guimarães, José Roberto
Environmental science and pollution research international 2017 v.24 no.7 pp. 6288-6298
Gram-negative bacteria, Vibrio fischeri, acute toxicity, antimicrobial properties, aqueous solutions, drugs, fluoroquinolones, free radicals, hydrogen peroxide, hydroxyl radicals, irradiation
Gatifloxacin, an antimicrobial drug belonging to the fluoroquinolone family, is active against Gram-positive and Gram-negative bacteria and is extensively used for the control of infections in humans. The presence of the drug in environmental matrices has already been reported. This study investigated the degradation of gatifloxacin in water by hydroxyl radicals generated by the UV₂₅₄ ₙₘ/H₂O₂ process ([Formula: see text] 0.4–2.4 mmol L⁻¹) and evaluated the capacity of the radicals to reduce the antimicrobial activity against Gram-positive and Gram-negative bacteria. Acute toxicity assays were performed with Vibrio fischeri, and the degradation products were proposed. The hydroxyl radicals formed in the processes were able to degrade the fluoroquinolone and remove the antimicrobial activity from the aqueous solution. Approximately 97 % gatifloxacin degradation was observed after applying 2.4 mmol L⁻¹ of initial H₂O₂ concentration and 20 min of UVC₂₅₄ₙₘ irradiation (130 J s⁻¹). The acute toxicity assays showed that the toxicity of the treated solution for V. fischeri increased as the gatifloxacin concentration in the solution decreased.