Alcohol based VS Quartenary Ammonium Compounds based Disinfectant / Hand Sanitiser

Types of Virus	Examples
Lipophilic / Enveloped	·    Herpes, Vaccinia, Influenza ·    Hepatitis B/C/D virus
Hydrophilic /Non-enveloped	·    Adenovirus, Enterovirus, Rotavirus*, Rhinovirus, Poliovirus

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Type	Alcohol-based	Quarternary ammonium compounds
Main active ingredient	60-95%  alcohol, usually isopropyl alcohol, ethanol (ethyl alcohol) or n-propanol Alcohol is known to be able to kill most germs – it is tuberculocidal, fungicidal, and virucidal but do not destroy bacterial spores.	e.g. Benzalkonium chloride
Mode of action (MOA)	The most feasible explanation for the antimicrobial action of alcohol is denaturation of proteins. This mechanism is supported by the observation that absolute ethyl alcohol, a dehydrating agent, is less bactericidal than mixtures of alcohol and water because proteins are denatured more quickly in the presence of water. Protein denaturation also is consistent with observations that alcohol destroys the dehydrogenases of Escherichia coli, and that ethyl alcohol increases the lag phase of Enterobacter aerogenes and that the lag phase effect could be reversed by adding certain amino acids. The bacteriostatic action was believed caused by inhibition of the production of metabolites essential for rapid cell division.	The bactericidal action of the quaternaries has been attributed to the inactivation of energy-producing enzymes, denaturation of essential cell proteins, and disruption of the cell membrane via releases of nitrogen and phosphorous from cells.
Coverage	Ethyl alcohol (ethanol) – at 60-80% concentration Isopropyl alcohol Lipid viruses V V Non-lipid viruses V X Hep. B Virus V V Hep. A Virus X No data HIV V Astrovirus V Methyl alcohol (methanol) has the weakest bactericidal action of the alcohols and thus seldom is used in healthcare.	Generally fungicidal, bactericidal, and virucidal against lipophilic/enveloped viruses (e.g., herpes, vaccinia, and influenza virus); however not all brands kill Hep B virus
		Less effective against Gram-negative bacteria than against Gram-positive bacteria
		Not sporicidal and generally not tuberculocidal or virucidal against hydrophilic /non-enveloped viruses (e.g. adenovirus, enterovirus, rhinovirus, poliovirus).
		Plus, poor mycobactericidal activities of quaternary ammonium compounds have been reported.
Diadvantage	·      Evaporates quickly - contact time not sufficient for killing, hence lack of residual action [Aqueous alcohol solutions are not appropriate for surface decontamination because of the evaporative nature of the solution; a contact time of ten minutes or more is necessary and not achievable using a 70% (v/v) aqueous solution of ethanol.] ·     Weakened by organic matter ·     Damages rubber & plastic ·     Flammable	·      High water hardness and materials such as cotton and gauze pads can make them less microbicidal because of insoluble precipitates or cotton and gauze pads absorb the active ingredients, respectively. ·      A few case reports have documented occupational asthma as a result of exposure to benzalkonium chloride ·      Limited effectiveness in soaps, detergents and hard water salts

·          CDC recommends washing hands with soap and water whenever possible because handwashing reduces the amounts of all types of germs and chemicals on hands. But if soap and water are not available, using a hand sanitizer with at least 60% alcohol can help you avoid getting sick and spreading germs to others.

·          Washing with warm water and soap remains the gold standard for hand hygiene and preventing the spread of infectious diseases.

·          Washing with warm water (not cold water) and soap removes oils from our hands that can harbour microbes.

·          There are important differences between washing hands with soap and water and cleaning them with hand sanitizer. For example, alcohol-based hand sanitizers don’t kill ALL types of germs, such as norovirus, some parasites, and Clostridium difficile. Hand sanitizers also may not remove harmful chemicals, such as pesticides and heavy metals like lead. Handwashing reduces the amounts of all types of germs, pesticides, and metals on hands.

References:

1.        https://www.cdc.gov/coronavirus/2019-ncov/infection-control/hcp-hand-hygiene-faq.html

2.        https://www.cdc.gov/infectioncontrol/guidelines/disinfection/disinfection-methods/chemical.html

3.        https://oncohemakey.com/disinfection-sterilization-and-control-of-hospital-waste/

4.        https://ehs.stanford.edu/reference/comparing-different-disinfectants

5.        https://www.sciencedirect.com/topics/neuroscience/quaternary-ammonium-compounds

6.        https://www.infectioncontroltoday.com/environmental-hygiene/comparison-commonly-used-surface-disinfectants

7.        https://www.canr.msu.edu/news/disinfectant-strategies-for-swine-facilities

8.        https://www.cdc.gov/handwashing/pdf/hand-sanitizer-factsheet.pdf

Source of diagrammes:

1.        http://www.cfsph.iastate.edu/pdf/antimicrobial-spectrum-of-disinfectants

2.        https://www.slideshare.net/doctorrao/handling-and-disposal-of-infectious-waste

3.        Kennedy et al.. Selection & Use of Disinfectants. University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources. Sept 2000.

All info accessed on 6 Apr 2020