S23: Mode-of-Action and Resistance to Oxidizing Agents: Recent Advances

Oxidising agents such as hydrogen peroxide, peracetic acid and chlorine dioxide are used extensively for high-level disinfection in the healthcare environment. Although, the activity of these microbicides is well-documented there is a paucity of information about their interactions with the microbial cells.

A large number of mode of action studies have been based on the use of empirical protocols such as leakage studies or visualization of cell damage using whole microorganisms, in particular, bacteria.  In these investigations it has often been difficult to determine the exact interaction with the microbial cell, since these microbicides have multiple target sites, particularly at a high concentration. Studying their effect against cell macromolecules offers a new insight in the difference in the mode of action of these oxidizing agents.

Gaining a better understanding of how they deliver their lethal activity is paramount for improving overall formulation efficacy but also for preventing microbial resistance. The occurrence of bacterial resistance to oxidizing agents at high (in use) concentration might be uncommon but is not impossible. Such a level resistance is likely to arise from multiple mechanisms working synergistically, since to date a single mechanism cannot confer high level resistance to these microbicides.