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Modes of action of three disinfectant active substances: a review
Stephen Wessels1, Hanne Ingmer
1DHI, Agern Allé 5, DK-2970 Hørsholm, Denmark.
Abstract:
This review deals with three categories of active substances for disinfectant products, their modes of action (MOA), and how MOA can help predict propensity for resistance in microorganisms. Within the European Union applications for approval of disinfectants of all kinds must be submitted in a few years, and documentation on MOA and resistance must be part of those applications. Peracetic acid is an unspecific, pervasive oxidizer of C-C double bonds and reduced atoms. This MOA would imply poor chance for development of resistance in microorganisms, as borne out by the absence of such reports in the literature. The quaternary ammonium compounds (QAC's) are much more specific in their antimicrobial mechanism. Even very low concentrations cause damage to the cytoplasmic membrane due to perturbation of the bilayers by the molecules' alkyl chains. Development of microbial resistance to QAC's, as well as cross-resistance to antibiotics, are particularly well documented. The polymer PHMB is antimicrobial because it disturbs the cell membrane's bilayer by interacting with it along the surface of the membrane. Resistance to the polymer appears not to develop despite many years of use in many fields. However, PHMB's toxicity to humans upon inhalation dictates great caution when deploying the substance.
Insights
Understanding disinfectant modes of action (MOA) is key to predicting microbial resistance. Peracetic acid and PHMB show low resistance risk, while quaternary ammonium compounds (QACs) have well-documented resistance issues.
Area of Science:
- Microbiology
- Antimicrobial Resistance
- Disinfectant Chemistry
Background:
- Disinfectant product approval in the EU will soon require data on mode of action (MOA) and microbial resistance.
- Understanding the MOA of active substances is crucial for predicting their propensity for resistance development.
Purpose of the Study:
- To review three categories of disinfectant active substances.
- To analyze their MOA and predict resistance potential.
- To inform future disinfectant applications and regulatory submissions.
Main Methods:
- Literature review of peracetic acid, quaternary ammonium compounds (QACs), and polyhexamethylene biguanide (PHMB).
- Analysis of reported mechanisms of action against microorganisms.
- Evaluation of documented cases of microbial resistance.
Main Results:
- Peracetic acid's non-specific oxidation MOA suggests low resistance development potential, supported by literature.
- QACs exhibit specific cytoplasmic membrane disruption, with well-documented resistance and cross-resistance to antibiotics.
- PHMB's surface membrane interaction MOA also shows low resistance development, but carries inhalation toxicity risks.
Conclusions:
- Disinfectant MOA directly correlates with resistance potential.
- Peracetic acid and PHMB are promising for low-resistance applications.
- QACs require careful use due to documented resistance, and PHMB necessitates caution due to toxicity.
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