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Increased Intracellular Hydrogen Peroxide Observed in Escherichia coli in the Presence of Two Classes of Antibiotics

Year: 2026
Type: article
Abstract: The modes of action of antibiotics on their target cells are well established. It has been shown previously that bactericidal classes of antibiotics stimulate hydroxyl radical production in cells as a result of the oxidative damage cellular pathway, in addition to their specific drug-target interactions; however, the production of reactive oxygen species (ROS) as a general cell death mechanism is a point of contention. This study aimed to investigate the effects of norfloxacin and tobramycin, two classes of bactericidal antibiotics, on growth rates and intracellular H O production of Escherichia coli. Three E. coli strains, BW25113 2 2 (the wild type), JW3914-1, and JW1721-1 ( ∆ katG and ∆ katE mutants respectively), were exposed to H O. Both mutants had a depressed growth rate compared to the wild type, 2 2 although growth was further reduced in ∆ katG, which is consistent with the role of KatG as the main catalase responsible for scavenging H O during log phase growth. When exposed 2 2 to sub-inhibitory levels of tobramycin and norfloxacin, results indicated that there was no difference between the growth of BW25113 or ∆ katG. A reporter system consisting of BW25113 transformed with a plasmid containing katG::luxCDABE was used to establish if norfloxacin and tobramycin indirectly induced the production of H O. Luminescence was 2 2 greater in the presence of tobramycin compared to norfloxacin, although both antibiotics did produce a signal. This experiment therefore supports the hypothesis that bactericidal antibiotics elicit the production of ROS, as indicated by the results of our lux reporter system.
DOI: 10.14288/ujemi.v16.203969
Language: English
Open Access status: green
OpenAlex ID: W7222817387
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