Disinfection mechanisms

Hugo W.B. (1992) Disinfection mechanisms. In Principles and Practice of Disinfection, Preservation and Sterilization, 2nd edn. (eds A.D. Russell, W.B. Hugo G.A.J. Ayliffe), pp. 187-210. Oxford Blackwell Scientific Publications. 

To study the action of the photocatalytic system at the genetical level of bacteria should contribute to the understanding of the bacterial disinfection mechanism. 

Hugo, W. B. (1992) Disinfection mechanisms. In Principles andPractice of Disinfection, Preservation and Sterilization... 

Gubler, M., Brunner, T.J., Zehnder, M., Waltimo, T Sener, B., and Stark, W.J. (2008) Do bioactive glasses convey a disinfecting mechanism beyond a mere increase in pH. International Endodontic Journal, 41(8), 670-8. 

The threat of accidental misuse of quaternary ammonium compounds coupled with potential harmful effects to sensitive species of fish and invertebrates has prompted some concern. Industry has responded with an effort to replace the questionable compounds with those of a more environmentally friendly nature. Newer classes of quaternaries, eg, esters (206) and betaine esters (207), have been developed. These materials are more readily biodegraded. The mechanisms of antimicrobial activity and hydrolysis of these compounds have been studied (207). AppHcations as surface disinfectants, antimicrobials, and in vitro microbiocidals have also been reported. Examples of ester-type quaternaries are shown in Figure 1. 

A number of disinfectants apparentiy owe their activity to formaldehyde, although there is argument on whether some of them function by other mechanisms. In this category, the dmg with the longest history is hexamethylenetetramine (hexamine, urotropin) [100-97-0] which is a condensation product of formaldehyde and ammonia that breaks down by acid hydrolysis to produce formaldehyde. Hexamine was first used for urinary tract antisepsis. Other antimicrobials that are adducts of formaldehyde and amines have been made others are based on methylolate derivations of nitroalkanes. The apphcations of these compounds are widespread, including inactivation of bacterial endotoxin preservation of cosmetics, metal working fluids, and latex paint and use in spin finishes, textile impregnation, and secondary oil recovery (117). 

Unrestricted use of reclaimed wastewater for drinking water, however, requires careful examination. While practically a complete barrier to viruses, bacteria, and other toxic entities that must be kept out of a potable supply, RO membranes could pose serious problems should any defect develop in their separation mechanism. Given the purity and clarity of RO-treated wastewaters, however, it might be advantageous to use RO and then subject the product to well-established disinfection procedures. 

Potassium permanganate is a strong oxidizing agent in acidic solution and is used to oxidize organic compounds and as a mild disinfectant. Its usefulness stems not only from its thermodynamic tendency to oxidize other species but also from its ability to act by a variety of mechanisms hence, it is likely to be able to find a path with low activation energy and act rapidly. 

The first mechanical variant uses a presoaked cotton swab on the surface covered with the disinfectant solution, the second variant uses a presoaked swab without disinfectant on the test surface. Both methods have been tested by Prof. Koller in Vienna and the first variant showed a higher efficacy than the second (using more disinfectant on the surface). 

It has been generally observed that the mechanical effects due to cavitational events are more responsible for the microbial disinfection and the chemical and heat effects play only a supporting role [56]. Microstreaming resulting from stable cavitation has been shown to produce stresses, sufficient to disrupt cell membranes... 

Different mechanisms to explain the disinfection ability of photocatalysts have been proposed [136]. One of the first studies of Escherichia coli inactivation by photocatalytic Ti02 action suggested the lipid peroxidation reaction as the mechanism of bacterial death [137]. A recent study indicated that both degradation of formaldehyde and inactivation of E. coli depended on the amount of reactive oxygen species formed under irradiation [138]. The action with which viruses and bacteria are inactivated by Ti02 photocatalysts seems to involve various species, namely free hydroxyl radicals in the bulk solution for the former and free and surface-bound hydroxyl radicals and other oxygen reactive species for the latter [139]. Different factors were taken into account in a study of E. coli inactivation in addition to the presence of the photocatalyst treatment with H202, which enhanced the inactivation... 

Silver and mercury salts have a long history of use as antibacterial agents.241-243 The use of mercurochrome ((40), Figure 18) as a topical disinfectant is now discouraged. Silver sulfadiazene (38) finds use for treatment of severe burns the polymeric material slowly releases the antibacterial Ag+ ion. Silver nitrate is still used in many countries to prevent ophthalmic disease in newborn children.244 The mechanism of action of Ag and Hg is through slow release of the active metal ion—inhibition of thiol function in bacterial cell walls gives a rationale for the specificity of bacteriocidal action. 

Starr JE, Judis J. 1968. Mechanism of action of phenolic disinfectants 8. Association of phenolic disinfectants with proteins. J Pharm Sci 57 768-773. 

Oyler, A.R., Llukkonen, R.J., Lukasewycz, M.T., Heikkila, K.E., Cox, D.A., and Carlson, R.M. Chlorine disinfection chemistry of aromatic compounds. Polynuclear aromatic hydrocarbons rates, products, and mechanisms. Environ. Sci. Technol, 17(6) 334-342, 1983. 

Scheme 1 Proposed mechanism for formation of iodo-DBPs with chlorine and chloramine disinfection (adapted from Bichsel and von Gunten [32, 33])...

Woo YT, Lai D, McLain JL, Manibusan MK, Dellarco V (2002) Use of mechanism-based structure-activity relationships analysis in carcinogenic potential ranking for drinking water disinfection by-products. Environ Health Perspect 110(suppl l) 75-87... 

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