Sublethal antibiotic treatment leads to multidrug resistance via radical-induced mutagenesis.
Antibiotic resistance arises through mechanisms such as selection of naturally occurring resistant mutants and horizontal gene transfer. Recently, oxidative stress has been implicated as one of the mechanisms whereby bactericidal antibiotics kill bacteria. Here, we show that sublethal levels of bactericidal antibiotics induce mutagenesis, resulting in heterogeneous increases in the minimum inhibitory concentration for a range of antibiotics, irrespective of the drug target. This increase in mutagenesis correlates with an increase in ROS and is prevented by the ROS scavenger thiourea and by anaerobic conditions, indicating that sublethal concentrations of antibiotics induce mutagenesis by stimulating the production of ROS. We demonstrate that these effects can lead to mutant strains that are sensitive to the applied antibiotic but resistant to other antibiotics. This work establishes a radical-based molecular mechanism whereby sublethal levels of antibiotics can lead to multidrug resistance, which has important implications for the widespread use and misuse of antibiotics.
Howard Hughes Medical Institute, Boston University, Boston, MA 02215, USA.
Michael A
MA
Kohanski
Mark A
MA
DePristo
James J
JJ
Collins
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects* / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D022761:Gene Transfer, Horizontal / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017382:Reactive Oxygen Species / Q000378:metabolism; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
D000900:Anti-Bacterial Agents; D017382:Reactive Oxygen Species