Introduction to Disinfectants

Effect of Alcohol on Bacteria and Viruses:
The Association of periOperative Registered Nurses (AORN) believes that alcohols in concentrations of 60-70% have a good effect on surgical scrub, so that they can quickly and greatly reduce skin bacteria. Rother believes that among skin disinfectants, alcohol has a faster antiseptic effect than other agents. Research has shown that alcohol-containing compounds may have a greater effect on resistant pathogens than disinfectant solutions alone.

Types of alcohol:
Ethanol
Medical alcohol or ethanol kills single-celled organisms and microbes by denaturing intracellular proteins, and the higher the concentration, the better ethanol does it. Its 70-85% solution is used as a disinfectant solution. Ethanol kills microorganisms by modifying proteins and breaking down fats. Of course, this action is only effective against bacteria, viruses and fungi.

Isopropanol
Isopropyl alcohol is an organic compound that has other names such as isopropanol and 2-propanol. This chemical is in the group of alcohol compounds and has a pungent odor similar to all alcohols. The use and role of Isopropyl alcohol is very important and prominent in health and medicine due to its antibacterial properties and it is used in the preparation and manufacture of soaps and lotions and is used in surgical operations as a skin disinfectant. Isopropyl evaporates at a similar rate to ethanol and kills bacterial and viral cells in the same way, but because it does less damage to living skin tissues, it is better for disinfecting the skin than ethanol.
Another advantage of Isopropyl alcohol over ethanol is that it is less toxic, so it is widely used as a solvent and cleaning fluid.

Hydrogen Peroxide
Extensive studies have shown that hydrogen peroxide has beneficial antibacterial, virucidal, sporicidal, and fungicidal effects.
The mechanism of action of hydrogen peroxide is the production of hydroxyl radicals. These hydroxyl radicals can attack membrane lipids, DNA, and other essential cellular components. 0.5% hydrogen peroxide solution can kill bacteria and viruses in one minute and remove mycobacteria and fungi from the environment in 5 minutes.
In studies with hydrogen peroxide solution at concentrations of 3% and 10%, it was observed that 10% solution is able to kill 1,000,000 spores of bacillus species in 60 minutes, and 3% solution does this in 150 minutes. The 7% solution kills spores within 6 hours, but kills mycobacteria in 20 minutes, fungi and viruses in 5 minutes, and bacteria in 3 minutes. Concentration of 6% to 25% hydrogen peroxide are considered as a chemical sterilizer. Ready-to-use solutions typically contain 7.5% hydrogen peroxide and 0.85% phosphoric acid (to maintain a low pH).

Peracetic Acid
Peracetic acid is known for its rapid effect on microorganisms, and one of its advantages is the absence of harmful by-products in nature, which eventually decompose into acetic acid, water and oxygen. Other advantage of this substance is its effectiveness at low temperatures and organic matter. The mechanism of action of peracetic acid is similar to that of other oxidizing agents, causing the degradation of proteins, disrupting cell wall permeability, and oxidizing sulfhydryl and sulfur groups in proteins and enzymes. Peracetic acid can kill gram-positive and gram-negative bacteria, fungi and yeasts in less than 5 minutes at a concentration of 100 ppm.
According to studies, the combination of peracetic acid and hydrogen peroxide kills all microorganisms in 20 minutes. A combination of 0.08% peracetic acid and 1% hydrogen peroxide performs better than glutaraldehyde-resistant mycobacteria.

Quaternary Ammonium Compounds
Quaternary ammonium compounds, commonly known as “quats”, are capable of killing a wide range of microbes. The effect of these compounds is particularly significant on gram-positive bacteria. This effectiveness can be seen even at low concentrations of these disinfectants.
A quat structure is a molecule containing nitrogen that is attached to four organic groups. The antimicrobial function of such a structure is that it can keep nutrients out of the reach of microorganisms and also prevent microbes from spreading their waste out.
The interesting thing about this group of disinfectants is that their use on surfaces can prevent the growth of microorganisms for a certain period of time.
If quaternary ammonium compounds (QACs) are prepared in high concentrations, they can be used as detergents; because in that case, they have lipophilic and hydrophilic properties.
Quats are prepared with different formulations according to the type of consumption. Proper use of these substances in food processing plants, schools, health care centers and homes, can significantly increase the level of health by reducing infections.
New quaternary ammonium compounds are used to disinfect surfaces and equipment. These compounds kill tubercle bacilli in 1 to 2 minutes and also have a high effect on viral agents.

Hospital Disinfectants
Disinfectants or antiseptics are a class of antimicrobials used on the surface of living skin and body tissues to kill or prevent the growth of bacteria, viruses, fungi, bacterial spores, and other organisms. This group of substances is basically separate from antibiotics, because antibiotics kill bacteria safely inside the body.
Disinfectants prevent infection, decay and septicemia. The use of disinfectants is essential for good health and is an important factor in preventing diseases, especially infectious diseases. The main difference between a disinfectant and an antibiotic is that disinfectants are only used externally and kill bacteria, while antibiotics enter the bloodstream after oral or injectable administration and have few side effects.
There are two categories of disinfectants: Bactericide disinfectants, which have the ability to directly kill a bacterial cell by destroying its wall, which leads to water absorption, swelling, and bursting, and bacteriostatic agents, which prevent bacterial growth and cell division.
Among the most important things that a hospital’s environmental health officer should have strict control over are hospital antiseptics and disinfectants, which we will discuss briefly below.
Disinfection is the elimination of large numbers of pathogenic microorganisms that are present on inanimate objects other than bacterial spores.
Few disinfectants can kill bacterial spores provided they have a long exposure time, which is called a chemical sterilizer.

Different Levels of Disinfection and Sterilization
Disinfection is done at three levels:

1. High level disinfection
2. Intermediate-level disinfection
3. Low level disinfection

The substances used in the hospital to control microorganisms and disinfect the hospital environment must have the following conditions:

• Has antimicrobial properties.
• Have a stable antimicrobial power.
• Soluble in water and other solvents.
• High durability and non-degradability of the material in a short time.
• Not toxic to humans and animals.
• Antimicrobial properties at body or room temperature.
• High permeability.
• Availability and cheapness.

Most important groups of antimicrobial agents:

1. Phenol and phenolic compounds: by denaturing bacterial proteins and destroying cell membranes.
2. Alcohols: In concentrations of 30-70% have the highest antimicrobial effect, such as ethyl alcohol.
3. Halogens: They contain iodine, chlorine and fluorine.
4. Heavy metal compounds: such as methane, silver and copper compounds.
5. Quaternary ammonium compounds: They are cationic detergents.
6. Aldehydes: such as glutaraldehyde and formaldehyde.
7. Gaseous materials: such as gaseous sterilizers.

Chemical disinfectants and antiseptics in the hospital are mainly of the following:

1. Chlorine: The compound used in this group is hypochlorite, which causes disinfection by releasing chlorine.
2. Iodine: Its 2% solution is used as disinfectant.
3. Betadine (Povidone-iodine): It is an iodine compound and has a high cleansing effect on bacterial spores and fungi.
4. Hydrogen peroxide: It is unstable and is used to disinfect wound pus, especially when the wound is dry. Always use hydrogen peroxide in solution, not pure.
5. Formic acid or Formaldehyde: A gaseous disinfectant that does not work well on bacterial spores but is very strong antimicrobial; In addition, it cannot safely kill anthrax and tetanus.
6. Phenol and its derivatives: It is used for disinfection of dishes contaminated with sputum and disinfection of toilets.
7. Cresol: It is used for disinfection of feces and sputum of patients.
8. Creolin: Solution of Cresol + an oil substance + soap is called Creolin, which is used to disinfect toilets at a rate of 5%.
9. Potassium permanganate: A very strong microbicide. In the presence of organic matter, its microbicidal effect is lost.
10. Detergents: Used to remove foreign matter and dirt near water.
11. Quaternary ammonium: It is a detergent and is used in disinfection of hospitals.
12. Afrooz: A cationic detergent that is used to disinfect the hospital environment and its equipment.
13. Halamid: For kitchen utensils, disinfecting toilets and disinfecting hands.
     

What is surgical scrub?
Scrub is the washing of hands before surgery. A technician who washes his hands during surgery and assists the surgeon during the operation is also called a scrub, and a technician who does not wash the hands and provides the surgeon and assistant surgeon (scrub) with the necessary equipment in the operating room is called a circular nurse.
How to wash the hands before surgery or the so-called scrub is a special method and you should pay attention to a series of points during this procedure.
One of the points is the duration of hand washing or scrubbing. There is disagreement about the duration of hand washing or scrubbing, but this time is at least three minutes and is defined as three minutes, four minutes, five, six and ten minutes, depending on the scrubbing methods.
Points for scrubbing (other than duration) are how to scrub or wash the hands; it should start with washing and scrubbing nails and fingers and then ending with the palm, back of the hand, wrist, forearm and arm about five to eight centimeters above the elbow. In addition, during the scrubbing or washing of the hands and after that, the hands should be kept above the forearm during all this time, so that the water that flows during the scrub pours from the fingertips and hands to the forearms and elbows and the surgeon and the assistant surgeon under no circumstances should keep the hands lower than the forearms and elbows.
The usual method is to wash the fingers, palms, back of the hands and wrists up to the top of the forearm for one minute with a disinfectant solution, then rinse, and then for at least three minutes with the available sterile brushes, washing the nails, fingers, hands, wrists, forearms and above the elbows are done and then rinsing is done again.
One of the things to keep in mind when scrubbing or washing your hands before surgery is that your hands should never come into contact with foreign objects, even the sink and faucet handle. Most operating rooms now have automatic valves that can be flushed without hand contact with the faucet, or handles that can be opened and closed with the help of another colleague, or the surgeon and the assistant surgeon with their own arm and part of the body which is not in the scrub or wash area, opens and closes the faucet.