Fig. 10: Proposed antimicrobial mechanisms of the Ob and colistin combination on colistin-resistant E. coli.

Ob acts synergistically with colistin to cause membrane permeabilization by displacing the membrane-stabilizing divalent ions ①. The Ob and colistin combination also causes dissipation PMF ② and inhibits drug efflux ③, resulting in accumulation of the two agents and disruption of electron transport chain activities, which in turn leads to further dissipation of PMF, reduction in efflux activities, and accumulation of the drugs ④. The collapse of PMF and extensive membrane damages result in cytosol leakage and eventually cell death ⑤. The figure was created using BioRender.