Disinfectants

Issues of Concern

The mechanism of action of disinfectants varies across different microorganisms, but the same techniques are used to study their effects on bacteria, fungi, and viruses. Among these, the antibacterial properties of disinfectants have been the most extensively researched, while studies on antiprotozoal effects are more limited due to challenges in culturing protozoa in laboratory settings. Disinfectants typically target the virus envelope, capsid, and genome. One issue that has been raised is that capsid destruction can release the viral genome. In some cases, these released nucleic acids may remain infectious. Therefore, both capsid destruction and further breakdown of the free nucleic acid should be considered in viral disinfection.[1]

Similar to antibiotics, there is concern about developing resistance to antiseptics and disinfectants, which makes the correct choice of disinfectant crucial.[2] Prion proteins, normally found on the surface of many cells, can cause brain damage when misfolded. These proteins are highly resistant to ordinary disinfectants, and no specific agent can effectively decontaminate tissues infected by transmissible degenerative encephalopathies.[1][3]

To better understand the coverage of each disinfectant, some of the most commonly used disinfectants in hospitals are mentioned below.

Alcohol

Alcohol has been widely used for centuries as a disinfectant and antiseptic. However, due to their lack of sporicidal activity, alcohol-based products are not recommended for sterilization. Their broad-spectrum antimicrobial activity works through membrane damage and cell lysis. To enhance the efficacy of alcohol-based products, they are sometimes combined with emollients (to reduce evaporation time) or with other biocides, such as chlorhexidine, which remains on the skin longer than alcohol.[1]

Aldehydes

Aldehyde disinfectants are classified into 3 essential categories, as mentioned below. 

• Glutaraldehyde is a dialdehyde with bactericidal properties. By binding to the outer layers of Escherichia coli and Staphylococcus aureus, glutaraldehyde provides coverage against gram-negative bacteria, has sporicidal properties, offers fungal coverage, and acts as a potent virucidal agent.[1] Glutaraldehyde is routinely used to clean medical equipment, such as endoscopes. Thorough rinsing of this disinfectant from the equipment is essential to prevent complications, such as colitis, following a colonoscopy.[4][5][6]

• Formaldehyde is a monoaldehyde used clinically as a sterilant and disinfectant. This disinfectant offers similar coverage to glutaraldehyde, including bactericidal, virucidal, and sporicidal effects, but works more slowly. Notably, formaldehyde reacts strongly with nucleic acids, which contributes to its carcinogenic properties. Therefore, appropriate personal protective equipment (PPE) and precautions are essential when handling this substance.[1][7]

• O-Phthalaldehyde is a potent bactericidal and sporicidal disinfectant with coverage similar to glutaraldehyde. O-Phthalaldehyde is suggested as a replacement for glutaraldehyde in endoscope disinfection.[8]

Anilides

Anilides possess antiseptic properties and are rarely used in hospital settings. They are primarily found in soaps and deodorants and provide coverage against gram-positive bacteria, with less effectiveness against gram-negative bacteria and fungi.[9]

Biguanides

• Chlorhexidine, a member of the biguanide family, is an antiseptic with broad-spectrum activity. Chlorhexidine binds rapidly to E coli and S aureus within 20 seconds and is highly resistant to Mycobacterium. The Centers for Disease Control and Prevention (CDC) and the United Kingdom's national evidence-based guidelines recommend using chlorhexidine to prepare the skin before central venous catheter insertion for children aged 2 months and older, as well as for adults. However, there are no specific recommendations for the choice of antiseptic for infants aged 2 months or older.[10][11]

Diamidines

Diamidines work by inhibiting oxygen uptake and inducing leakage of amino acids. They provide coverage against Pseudomonas aeruginosa and Enterobacter cloacae, making them suitable for topical treatment of wounds.[1]

Halogen-Releasing Agents

• Chlorine-releasing agents (CRAs) are highly active oxidizing agents. Sodium hypochlorite, a common CRA, is widely used as a surface disinfectant (bleach) in both home and hospital settings to disinfect surfaces contaminated with HIV or HBV. CRAs are effective as sporicidal, bactericidal, and virucidal agents.[12]

• Iodine-based agents are less reactive than chlorine but act rapidly. Povidone-iodine, a well-known example, has been used as an antiseptic and disinfectant for centuries, although it is associated with significant staining and skin irritation. Compared to CRAs, iodine-based agents are less effective against fungi and spores.

Silver Compounds

Silver compounds are used to treat warts, eye infections, and burn wounds. Commonly used silver compounds include silver nitrate and silver sulfadiazine, which are effective against Cryptococcus neoformans and P aeruginosa.

Peroxygens

• Hydrogen peroxide (H₂O₂) is a well-known colorless liquid biocide commonly used as a disinfectant, sterilant, and antiseptic in both hospitals and homes. Available in various concentrations, H₂O₂ is considered environmentally friendly due to its decomposition into oxygen and water. H₂O₂ is highly effective against both gram-positive and gram-negative bacteria and exhibits sporicidal activity at higher concentrations (10% to 30%).

• Peracetic acid is a more potent biocide than H₂O₂ and is used as a sterilant for medical devices, scopes, and hemodialyzers. This acid is effective against bacteria, viruses, and fungi at lower concentrations than H₂O₂.

Quaternary Ammonium Compounds

Quaternary ammonium compounds are used as skin antiseptics preoperatively and can be applied to mucous membranes. They are also found in deodorants and disinfectants for hard surfaces.[13]

Clinical Significance

Hospital-acquired infections, also known as healthcare-associated infections (HAI), manifest 48 hours after hospital admission. Some of the most persistent pathogens in healthcare settings include Clostridium difficile, vancomycin-resistant enterococci, and methicillin-resistant S aureus. Please see StatPearls' companion resource, "Hospital-Acquired Infections," for more information.  

The rate of these potentially deadly infections can be reduced by following precautionary signs at patient room doors, ensuring clear communication between interprofessional healthcare teams, and providing proper education on the most effective disinfectants for these pathogens. Familiarity with different types of disinfectants, their coverage, proper usage, and adherence to scheduled cleaning can significantly reduce HAIs and improve patient outcomes.[14][15]

Nursing, Allied Health, and Interprofessional Team Interventions

Reducing the rate of HAIs requires the active participation of everyone in the healthcare setting, including physicians, nurses, pharmacists, and lab technicians, as well as patients. Each healthcare professional plays a vital role in minimizing the risk of transmission through proper cleaning, disinfection, and the correct use of PPE. By following established guidelines, nurses are at the forefront of HAI prevention.[16]