The Role of Reactive Oxygen Species in Antibiotic-Induced Cell Death in Burkholderia cepacia Complex Bacteria

• Published in: PloS one Vol. 11; no. 7; p. e0159837
• Main Authors: Van Acker, Heleen, Gielis, Jan, Acke, Marloes, Cools, Freya, Cos, Paul, Coenye, Tom
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 20.07.2016; Public Library of Science (PLoS)
• Subjects: Analysis; Anti-Bacterial Agents - pharmacokinetics; Anti-Bacterial Agents - pharmacology; Antibiotics; Antioxidants; Apoptosis; Bacteria; Biofilms; Biofilms - drug effects; Biofilms - growth & development; Biology and Life Sciences; Burkholderia cenocepacia; Burkholderia cepacia; Burkholderia cepacia complex - drug effects; Burkholderia cepacia complex - growth & development; Burkholderia cepacia complex - metabolism; Burkholderia Infections - drug therapy; Burkholderia Infections - metabolism; Burkholderia Infections - microbiology; Carbonyls; Cell death; Cell Death - drug effects; Ciprofloxacin; Ciprofloxacin - pharmacology; Deoxyribonucleic acid; DNA; DNA damage; E coli; Electron paramagnetic resonance; Enzymes; Escherichia coli; Free radicals; Gene expression; Gene Expression Regulation, Bacterial - drug effects; Hydrogen peroxide; Hydroxyl radicals; Hygiene; Laboratories; Medicine and Health Sciences; Meropenem; Microbial Sensitivity Tests; Oxidation; Oxidative stress; Oxygen; Parasitology; Pharmaceuticals; Physical Sciences; Physiological aspects; Proteins; Pseudomonas aeruginosa; Reactive oxygen species; Reactive Oxygen Species - metabolism; Repressor Proteins - biosynthesis; Research and Analysis Methods; Respiration; Spectrophotometry; Streptococcus infections; Thienamycins - pharmacology; Thoracic surgery; Tobramycin; Tobramycin - pharmacology; Belgium
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0159837

It was recently proposed that bactericidal antibiotics, besides through specific drug-target interactions, kill bacteria by a common mechanism involving the production of reactive oxygen species (ROS). However, this mechanism involving the production of hydroxyl radicals has become the subject of a lot of debate. Since the contribution of ROS to antibiotic mediated killing most likely depends on the conditions, differences in experimental procedures are expected to be at the basis of the conflicting results. In the present study different methods (ROS specific stainings, gene-expression analyses, electron paramagnetic resonance, genetic and phenotypic experiments, detection of protein carbonylation and DNA oxidation) to measure the production of ROS upon antibiotic treatment in Burkholderia cepacia complex (Bcc) bacteria were compared. Different classes of antibiotics (tobramycin, ciprofloxacin, meropenem) were included, and both planktonic and biofilm cultures were studied. Our results indicate that some of the methods investigated were not sensitive enough to measure antibiotic induced production of ROS, including the spectrophotometric detection of protein carbonylation. Secondly, other methods were found to be useful only in specific conditions. For example, an increase in the expression of OxyR was measured in Burkholderia cenocepacia K56-2 after treatment with ciprofloxacin or meropenem (both in biofilms and planktonic cultures) but not after treatment with tobramycin. In addition results vary with the experimental conditions and the species tested. Nevertheless our data strongly suggest that ROS contribute to antibiotic mediated killing in Bcc species and that enhancing ROS production or interfering with the protection against ROS may form a novel strategy to improve antibiotic treatment.