CM/Spotlight: Infection Control The Science Of Disinfectants Why they work and what you should know to maximize their effectiveness. By: Kirsten Thompson W Alcohol We often take for granted the action of disinfec-tants without fully understanding how they work. Not only are there differences in the action of the antimicrobial ingredients, but there are also differences depending on the concentration of chemical that is used that can impact the action of a chemical agent or physical process. In general, disinfectants have three mecha-nisms of action or ways that they affect or kill an organism: Cross-linking, coagulating, clumping; structure and function disruption; and oxidizing. most effect on the bacterial cell, targeting some key metabolic enzymes and destroying the organism. Chlorine compounds have also been shown to affect surface antigen in enveloped viruses and deoxyribonucleic acid (DNA) as well as structural alterations in non-enveloped viruses. Very few chemicals are considered sporicidal; however, chlorine compounds in higher concentra-tions have been shown to kill bacterial spores such as Clostridium difficile ( C. diff ). Peroxygen Compounds Mechanism of action: Oxidizing. Both hydrogen peroxide and peracetic acid are peroxygen compounds of great importance in infection control because, unlike like most dis-infectants, they are unaffected by the addition of organic matter and salts. In addition, the formation of the hydroxyl radi-cal, a highly reactive ion that occurs as peroxygen compounds encounter air, is lethal to many spe-cies of bacteria because it is a strong oxidant. Being highly reactive, the hydroxyl radical attacks essential cell components and cell mem-branes, causing them to collapse. Peroxygen compounds also kill spores by removing proteins from the spore coat, exposing its core to the lethal disinfectant. Kirsten M. Thompson is a Senior Program Leader at Ecolab’s Research, Development and Engineering facility in Eagan, Minnesota. Her department is responsible for regulatory data quality of all Ecolab Healthcare antimicrobial products. For more information, visit www.EcolabHealthcare.com. Mechanism of action: Cross-linking, coagulating, clumping. Like many disinfectants, alcohols are gener-ally considered to be non-specific antimicrobials because of their many toxic effects. Alcohols cause cell proteins to clump and lose their function. Specifically, the cell membranes lose their structure and collapse, thereby killing it. The alcohol must be diluted with water for the optimum effect, as proteins are not denatured as readily with straight alcohol. Alcohol is also effective in inhibiting spore ger-mination by affecting the enzymes necessary for germination. However, once it’s removed, spores can recov-er, so it’s not considered a sporicidal. Phenol Mechanism of action: Cross-linking, coagulating, clumping. Phenol and its derivatives exhibit several types of bactericidal action. At higher concentrations, the compounds pen-etrate and disrupt the cell wall and make the cell proteins fall out of suspension. One of the first things to occur is stopping essential enzymes. The next level in the damage to the bacteria is the loss in the membrane’s ability to act as a barrier to for more info Visit www.cmmonline.com and type in search key-word: Infection Control . For more information on related products, visit www.cmmonline.com , select SUPPLIER SEARCH from the main navigation bar, and enter keyword: Disinfection . Chlorine Mechanism of action: Oxidizing. Chlorine is a very common disinfectant used in a wide variety of cleaning solutions and applications — even in drinking water — because, even in very small amounts, it exhibits fast bactericidal action. Chlorine works by oxidizing proteins, lipids and carbohydrates. Hypochlorous acid, which is a weak acid that forms when chlorine is dissolved in water, has the 28 CM/Cleaning & Maintenance Management ® • February 2012
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