Synergistic efficacy of Bisbenzimidazole and Carbonyl Cyanide 3-Chlorophenylhydrazone combination against MDR bacterial strains

Abstract

Activation of efflux systems and the formation of biofilm are majorly adapted by microbes to resist antimicrobial agents. PPEF (bisbenzimidazole) targeting topoisomerase IA is observed to be an effective bactericidal agent against both Gram-positive and Gram-negative bacterial strains and thus can be developed as potent broad-spectrum antibiotic against MDR strains. PPEF treatment did not cause target specific mutation instead it leads to up-regulation of efflux gene in E. coli K12 as a mechanism of resistance. Microscopy, fluorescence spectroscopy and flow cytometry result demonstrate higher accumulation of PPEF in efflux gene deleted E. coli K12 mutants, and also suggest that Carbonyl Cyanide 3-Chlorophenylhydrazone (CCCP), resist the efflux of PPEF, and thus increases efficacy of PPEF. Herein, we report, PPEF and CCCP synergistically killed the persistent bacterial cells, which are not killed by PPEF alone. The above two compounds together inhibited biofilm formation, eradicate preformed biofilms and kills the biofilm cells of P. aeruginosa. PPEF and CCCP together reduced bacterial load of E. coli ATCC25922 by 6 log10 in neutropenic thigh infection model of balb/c mice. Present study suggests that combination therapy could be a promising antimicrobial strategy to handle MDR pathogenic strains.

Gram-negative synergy and mechanism of action of alkynyl bisbenzimidazoles

“…Bisbenzimidazoles have been shown to inhibit bacterial topoisomerase IA independently many times across a wide variety of compounds sharing the bisbenzimidazole backbone, leading to expectations of a possible novel antibacterial mechanism 7–9 . Docking studies have proposed that bisbenzimidazoles bind to the active site of topoisomerase IA, forming a ternary complex with DNA and the enzyme, and inducing double-stranded DNA breaks which can lead to cell death.…”

“…S19, Tables S16 & S17) 27 . Previous studies of other bisbenzimidazole libraries posit bisbenzimidazoles as substrates of active efflux, indicating combination with efflux inhibitors may be an effective route for improvement of coverage 7 . Alkynyl-bisbenzimidazole compounds contain long hydrophobic alkynyl linkers that may interact with the outer membrane of Gram-negative bacteria, therefore combination efficacy with membrane active antibiotics was investigated.…”

“…This study supports that bisbenzimidazoles with hydrophobic moieties have potential for further target drug development 6 . More recently, these bisbenzimidazole derivatives were described to have broad spectrum bacterial coverage when used in combination with carbonyl cyanide 3-chlorophenylhydrazone, an efflux pump inhibitor 7 .…”

An antibacterial compound pyrimidomycin produced by Streptomyces sp. PSAA01 isolated from soil of Eastern Himalayan foothill

“…To determine the combinatorial effect of pyrimidomycin with the most common antibiotics used in the present treatment regimen, on bacterial pathogens, we have used the preliminary checkerboard method according to the standard protocol 37 . The concentrations of all antibiotics used for the experiment were MIC to 1/4 MIC.…”

Effect of new carbonyl cyanide aromatic hydrazones on biofilm inhibition against methicillin resistant Staphylococcus aureus

“…4,14,15 CCCP in combination with small molecules showed synergistic effect against most of the MDR pathogenic bacterial strains. [16][17][18][19][20] CCCP in combination with antibiotics could potentiate antibacterial activity.…”