Susceptibility of colistin-resistant pathogens to predatory bacteria.

The increase in multidrug-resistant Gram-negative bacterial infections has forced the reintroduction of antibiotics such as colistin. However, the spread of the plasmid-borne mcr-1 colistin resistance gene have moved us closer to an era of untreatable Gram-negative infections. To evaluate whether predatory bacteria could be used as a potential therapeutic to treat this upcoming threat, the ability of Bdellovibrio bacteriovorus and Micavibrio aeruginosavorus to prey on several clinically relevant mcr-1-positive, colistin-resistant isolates was evaluated. No change in the ability of the predators to prey on free swimming and biofilms of prey cells harboring mcr-1 was measured, as compared to their mcr-1 negative strain.