Disinfectant | EPFL Graph Search

A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, which is an extreme physical or chemical process that kills all types of life. Disinfectants are generally distinguished from other antimicrobial agents such as antibiotics, which destroy microorganisms within the body, and antiseptics, which destroy microorganisms on living tissue. Disinfectants are also different from biocides—the latter are intended to destroy all forms of life, not just microorganisms. Disinfectants work by destroying the cell wall of microbes or interfering with their metabolism. It is also a form of decontamination, and can be defined as the process whereby physical or chemical methods are used to reduce the amount of pathogenic microorganisms on a surface. Disinfectants can also be used to de

Impact of virus aggregation on disinfection

Vincent Genicoud

This study is based on the hypothesis that viral aggregation slows the inactivation by chemical disinfectants. This slow-down depends on the aggregate size, the concentration and the reactivity of the disinfectant. In this work we test this hypothesis by experimentally investigating the inactivation MS2 coliphage aggregates by dichloramine and PhiX174 aggregates by PAA. The experiments performed with MS2 and dichloramine show good adherence to the theory. We observed that inactivation by dichloramine was slowed by 3.4 to 13 times with aggregates of size between 420 and 580 nm, and with a dichloramine concentration varying between 3.5 and 13 mg/L. The larger the aggregates, and the higher the concentration of disinfection, the greater was the observed inhibition of inactivation due to aggregates. Comparing the inactivation of MS2 by dichloramine and by PAA, we observed that dichloramine was a stronger disinfectant, and the impact of aggregation on dichlormaine was more extensive. This permitted to verify the hypothesis that a more reactive disinfectant was more sensitive to aggregation. Our results were furthermore in good agreement with the mechanistic model for the inactivation of viral aggregates developed by Mattle et al. (2011). In contrast to MS2, results for the disinfection of aggregates of PhiX174 did not exhibit an effect of aggregation on disinfection. We hypothesize that PhiX174 viruses within aggregates were not sufficiently compact to result in inhibition of disinfection. This phenomenon was probably due to the spikes on the PhiX174 capsid. Structural features of viral aggregates thus influence their propensity to inhibit inactivation.

2012

Determination of variables influencing the effectiveness of disinfection of surface water used for human consumption in Costa Rica

Clara Barret

Disinfection of water for human consumption is a challenge to ensure that water is free of pathogens and pollutants while avoiding the formation of potentially harmful undesirable products. The establishment of disinfection facilities must take into account the local context as well as technical and economic feasibility to ensure their sustainability. Chlorination is a disinfection technique that is widely used throughout the world and can take several forms. However, this technique can lead to the formation of disinfection by-products, some of which are harmful to human health and are a source of growing concern. This present report focuses on chlorination using tablets that release chlorine when eroded by contact with water. This study aimed at improving the understanding of the effect of various parameters on the efficiency of water chlorination in the Cartago region (Costa Rica). First a chlorination facility located in a village near Cartago was studied. The purpose of this assessment was to diagnose the current situation, determine the changes needed to improve it and implement them. It was showed that the chlorine concentration delivered by this facility was too low and variable. A new chlorinator and a tank allowing a better mixing of the chlorinated solution have been installed. These modifications have resulted in a higher and more homogeneous chlorine concentration in the storage tanks and an improvement in some water quality parameters. On the basis of the results, recommendations were made to ensure the proper functioning of the facility and the continuation of measurements during future campaigns. It should be noted that this was a short-term study, measurements over a longer period would allow more precise conclusions to be drawn. The second part of the project concerned 10 chlorination facilities in the Cartago region. The purpose was to compare the results of various parameters of surface and groundwater samples collected in the rainy/transition season in 2018 with those of the 2019 dry season. For the moment there were thus only two series of data but this has nevertheless allowed us to observe an improvement in certain parameters during the dry season. Future measurements campaigns will consolidate these results.

2019

Genetic, structural and phenotypic properties of MS2 coliphage with resistance to ClO2 disinfection

Virginie Bachmann, Anna Carratala Ripolles, Ricardo Cesar Guerrero Ferreira, Tamar Kohn, Petr Leiman, Sergey Nazarov, Laura Piccinini, Qingxia Zhong

Common water disinfectants like chlorine have been reported to select for resistant viruses, yet little attention has been devoted to characterizing disinfection resistance. Here, we investigated the resistance of MS2 coliphage to inactivation by chlorine dioxide (ClO2). ClO2 inactivates MS2 by degrading its structural proteins, thereby disrupting the ability of MS2 to attach to and infect its host. ClO2-resistant virus populations emerged after repeated cycles of ClO2 disinfection followed by regrowth, but also after dilution-regrowth cycles in the absence of ClO2. The resistant populations exhibited several fixed mutations which caused the substitution of ClO2-labile by ClO2-stable amino acids. On a phenotypic level, these mutations resulted in a more stable host binding during inactivation compared to the wild-type, thus resulting in a greater ability to maintain infectivity. This conclusion was supported by cryo-electron microscopy reconstruction of the virus particle, which demonstrated that most structural modification occurred in the putative A protein, an important binding factor. Resistance was specific to the inactivation mechanism of ClO2 and did not result in significant cross-resistance to genome-damaging disinfectants. Overall, our data indicate that resistant viruses may emerge even in the absence of ClO2 pressure, but that they can be inactivated by other common disinfectants.

Amer Chemical Soc2016

Determination of variables influencing the effectiveness of disinfection of surface water used for human consumption in Costa Rica

Clara Barret

2019