Synergistic action of indole-3-carbinol with membrane-active agents against multidrug-resistant Gram-negative bacteria.

This article investigates the synergistic antimicrobial effects of indole-3-carbinol (I3C), a natural compound derived from cruciferous vegetables, combined with membrane-active agents—specifically ethylenediaminetetraacetic acid (EDTA) and carbonyl cyanide 3-chlorophenylhydrazone (CCCP)—against multidrug-resistant (MDR) Gram-negative bacteria. The study demonstrates that EDTA significantly enhances the bactericidal activity of I3C against clinical MDR isolates of Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli, reducing minimal inhibitory concentrations (MICs) by 8- to 64-fold and effectively decreasing bacterial persister cells. CCCP showed synergistic effects with I3C primarily against P. aeruginosa and A. baumannii but was less effective against K. pneumoniae and E. coli. The findings suggest that combining I3C with membrane-permeabilizing agents like EDTA may offer a promising strategy to improve antimicrobial efficacy against MDR Gram-negative pathogens, although potential adverse effects of EDTA warrant careful consideration.