Mechanisms of action of disinfectants

Disinfectants and biocides are a chemically diverse group of agents which are generally considered to exhibit poor selective toxicity. This should not be mistaken for poor target specificity, however, and much is now known concerning the damaging interactions which may arise between bacterial cell and disinfectant agent. Critical governing features of these interactions are the physicochemical characteristics of the chemical agent, cell morphology, and the physiological status of the microorganism. Antibacterial events include membrane disruption, macromolecule dysfunction, and metabolic inhibition; the consequential effect is determined by the relative contribution(s) of the target(s) to microbial cell survival and the possible initiation of self-destructive processes. Disinfection kinetics offer a measure to differentiate between physiochemical and chemical interactions. Increasingly demanding disinfectant applications require more sophisticated use of biocidal systems. Approaches include: agents in combination, whereby a knowledge of mechanism of action assists in designing optimal mixtures; intracellular biocide delivery, using cellular transport processes to overcome cellular barriers; and targeted donation of biocide from delivery systems, requiring an understanding of target reactivity. A knowledge of disinfection mechanisms provides a basis from which novel chemistries and synergistic combinations may be developed.