Real-time single-cell imaging reveals accelerating lipid peroxyl radical formation in Escherichia coli triggered by a fluoroquinolone antibiotic

MARTINEZ, SOL R; DURANTINI, ANDRÉS M.; BECERRA, MARIA CECILIA; COSA, GONZALO

ACS Infectious Diseases

ACS Publications

Año: 2020

2373-8227

Formation of reactive oxygen species (ROS) induced by bactericidal antibiotics has been associated with a common, non-specific, mechanism of cellular death. Herein we report real-time single cell fluorescence studies on E. coli stained with a fluorogenic probe for lipid peroxyl radicals showing generation of this form of ROS when exposed to the minimum inhibitory concentration (MIC) and 10xMIC of the fluoroquinolone antibiotic ciprofloxacin (3 and 30 μM, respectively). Single-cell intensity-time trajectories show an induction period followed by an accelerating phase for cells treated with antibiotic, where initial and maximum intensity achieved following 3.5 h incubation with antibiotic showed dose dependent average values. A large fraction of bacteria remains viable after the studies, indicating ROS formation is occurring a priori of cell death. Punctate structures are observed, consistent with membrane blebbing. Addition of a membrane embedding lipid peroxyl radical scavenger,