Given the COVID-19 pandemic, I think it would be impractical to discuss the different types of hand sanitizers available and how to evaluate their effectiveness in killing bacteria.
All hand sanitizers are different. Certain ingredients do produce anti-microbial effects. Choose a hand sanitizer based on the bacteria, fungi and viruses you want to inactivate. There is no hand cream that can kill everything. In addition, even if it does exist, it will have negative health consequences.
Some hand sanitizers are advertised as “alcohol-free”, probably because they have less dry skin. These products contain benzalkonium chloride, a chemical that is effective against many bacteria, certain fungi and protozoa. It is ineffective against Mycobacterium tuberculosis, Pseudomonas bacteria, bacterial spores and viruses. The presence of blood and other organic substances (dirt, oil, etc.) that may be present on the skin can easily inactivate benzalkonium chloride. The soap remaining on the skin will neutralize its bactericidal effect. It is also easily contaminated by Gram-negative bacteria.
Alcohol is effective against Gram-positive and Gram-negative bacteria, many fungi, and all lipophilic viruses (herpes, vaccinia, HIV, influenza and coronavirus). It is not effective against non-lipid viruses. It is harmful to hydrophilic viruses (such as astrovirus, rhinovirus, adenovirus, echovirus, enterovirus and rotavirus). Alcohol cannot kill the polio virus or hepatitis A virus. It also does not provide continuous antibacterial activity after drying. Therefore, it is not recommended as an independent preventive measure. The purpose of alcohol is in combination with a more durable preservative.
There are two types of alcohol-based hand gels: ethanol and isopropanol. 70% alcohol can effectively kill common pathogenic bacteria, but is ineffective against bacterial spores. Keep your hands moist for two minutes for maximum results. Random rubbing for a few seconds cannot provide sufficient microbial removal.
Isopropanol has advantages over ethanol because it is more bactericidal in a wider concentration range and less volatile. To obtain the antibacterial effect, the minimum concentration must be 62% isopropanol. The concentration decreases and the efficacy decreases.
Methanol (methanol) has the weakest antibacterial effect of all alcohols, so it is not recommended as a disinfectant.
Povidone-iodine is a bactericide that can effectively fight against many bacteria, including gram-positive and gram-negative bacteria, certain bacterial spores, yeast, protozoa, and viruses such as HIV and hepatitis B virus. The antibacterial effect depends on the concentration of free iodine in the solution. It takes at least two minutes of skin contact time to be effective. If not removed from the skin, povidone-iodine can continue to be active for one to two hours. The disadvantage of using it as a preservative is that the skin becomes orange-brown and there is a risk of allergic reactions, including allergic reactions and skin irritation.
Hypochlorous acid is a natural molecule produced by the body’s own white blood cells. Has a good disinfection ability. It has bactericidal, fungicidal and insecticidal activities. It destroys structural proteins on microorganisms. Hypochlorous acid is available in gel and spray forms and can be used to disinfect surfaces and objects. Studies have shown that it has virus-killing activity against avian influenza A virus, rhinovirus, adenovirus and norovirus. Hypochlorous acid has not been specifically tested on COVID-19. Hypochlorous acid formulations can be purchased and ordered over the counter. Don’t try to make yourself.
Hydrogen peroxide is active against bacteria, yeast, fungi, viruses and spores. It produces hydroxyl free radicals that damage cell membranes and proteins, which are essential for the survival of microorganisms. Hydrogen peroxide decomposes into water and oxygen. The over-the-counter hydrogen peroxide concentration is 3%. Don’t dilute it. The lower the concentration, the longer the contact time.
Baking soda can be used to remove stains on the surface, but it is completely ineffective as an antibacterial agent.
Although hand sanitizer helps reduce the risk of COVID-19 infection, it cannot replace soap and water. Therefore, remember to wash your hands thoroughly with soap and water after returning home from a business trip.
Dr. Patricia Wong is a dermatologist at the Palo Alto Private Clinic. For more information, please call 473-3173 or visit patriciawongmd.com.
Post time: Aug-19-2020