Surface Disinfection
Still vitally important.
by Nancy Andrews, RDH
How important is environmental disinfection?
In 2007, the Centers for Disease Control and Prevention (CDC) investigated a case of Hepatitis B transmission from one dental patient to another, after the exact strain of virus was identified in two oral surgery patients seen in the same practice on the same day. The infection control practices of the office were reported to be excellent. When all other means of transmission were ruled out, possible failure of surface disinfection practices was suggested as the most likely problem.
This case reinforces a few basic infection control concepts, including: 1) reminding us that some pathogens are relatively resistant outside of the body and can remain active on environmental surfaces, and 2) effective surface disinfection is important every time it is done and that even with excellent asepsis practices, pathogen transmission from environmental surfaces is still possible. As mundane as clinical asepsis seems, its importance is clear. This article targets a few areas of common confusion related to the importance of cleaning along with disinfection.
Investigation of illness and deaths linked to healthcare suggest that environmental surfaces and items have the
potential to harbor infectious organisms that may be transferred by hands, instruments, equipment and other contact. Unseen contaminants of major concern are bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). S.
aureus is able to remain viable in dried blood and exudate on environmental surfaces for weeks. In fact, most staphylococcal strains have been shown to survive for weeks to months on contaminated inanimate surfaces. Viruses such as influenza and rhinoviruses from nasal secretions can survive for hours or even days on items such as handkerchiefs, pens, doorknobs and countertops. Hepatitis B Virus can persist in dried blood for seven days on surfaces, and can remain viable on surfaces even in the absence of visible blood.
Confusion about cleaning and disinfection
Cleaning reduces micro-organisms and removes physical matter that can interfere with disinfection. In spite of advertised "single-step disinfectants," disinfection is only possible on pre-cleaned surfaces. Since contamination is not always visible, cleaning is the essential first step of disinfection. Here are some cardinal rules for using intermediate-level surface disinfectants (for a more detailed breakout, visit www.firstimpressionsmag.com):
- Always clean before disinfecting surfaces.
- Use an effective cleaning product as a first step.
- If different products are used for step one and step two, they should be chemically compatible.
- Allow the disinfectant to remain wet on the surface for the recommended contact time during the disinfection step.
- When choosing a disinfectant, optimize these features: (no one product is perfect!)
- Broadest spectrum of antimicrobial activity
- Fastest antimicrobial activity
- Maximum effectiveness in the presence of organic material
- Non-toxic and non-allergenic
- Surface and material compatibility: minimal damage to surfaces or materials
- Residual effect on treated surfaces
- Minimal odor
- Ease of use
- Economy; purchase cost and related costs, such as paper towels, employee time, damage to materials.
Wipes vs. sprays
Convenient pre-saturated wipes are increasingly popular. Compared to sprays; wipes reduce liquid overspray, drips, aerosols and penetration into materials and equipment.
Wipes’ effectiveness depends on technique, saturation and the disinfecting properties of the solution. Wipes saturated with sufficient disinfectant solution (to remain wet for the recommended contact time) are as effective as spraying the same product. Pre-saturated EPA-approved professional wipes have been officially tested for efficacy.
Making "wipes" not recommended
Instead of buying wipes, some offices prefer to "make their own." If liquid disinfectant is poured over gauze or other material, the interaction between the solution and material is unknown, and the stability of the disinfectant can not be guaranteed. Most disinfectant manufacturers do not recommend this practice. Instead, the wipe may be sprayed or soaked at the time of use. Pre-saturated wipes save valuable employee time.
Use one product for both spray and wipes
Offices that use both sprays and wipes should consider one product that comes in both forms to avoid use of dissimilar and possibly damaging chemicals. Pump spray bottles are recommended over aerosol cans to reduce airborne chemical exposure.
Alcohol content
"Water-based" disinfectants have no or low levels of alcohol, while high alcohol products are considered "alcohol-based." Alcohol is often added to disinfectants to enhance their effectiveness against TB, or to enhance the effectiveness of other active ingredients. For example, simple quaternary ammonium products do not kill TB, but alcohol may be added to provide effectiveness against TB, creating an intermediate level disinfectant. Alcohol levels may be raised to shorten a disinfectant’s TB kill time, but high alcohol content does not always guarantee fast TB times. Popular alcohol-based products range from 1- to 10-minute contact times for TB effectiveness. High alcohol products may precipitate organic materials rather than lifting them off the surface. Therefore, products with high amounts of alcohol may be less effective cleaners of organic material and are often sold with separate pre-cleaning products such as foaming cleaners. In contrast, most water-based products, with or without alcohol, can be used for both cleaning and disinfection, avoiding the need for two products. Recommended contact time for "TB kill" must be observed.
Alcohols are known to dry and possibly damage plastics and be corrosive to metals, so caution should be taken.
The bottom line
Surface cleaning and disinfection is vitally important, because cross-infection may occur. Cleaning is an essential part of achieving disinfection, and must be understood and performed. Some disinfection products clean well and others do not. If a disinfectant has good cleaning capabilities, it can be used for both cleaning and disinfection. If a disinfectant requires a separate pre-cleaning product, the two products should be chemically compatible and used properly. Sufficient amounts of solution, applied thoroughly and left for the recommended contact time are essential to disinfect on pre-cleaned surfaces.
Nancy Andrews is a nationally recognized speaker, educational consultant, and author; focusing on disease risks, infection prevention, and ergonomics. She is on the California Dental Association, American Dental Association and Organization of Safety and Asepsis Procedures (OSAP) speakers’ bureaus. Contact her at http://nancyandrewsrdh.net
Sidebar:
Common errors related to surface disinfection
- Omitting the cleaning step.
- Shortening the recommended contact time.
- Using a high alcohol product to clean surfaces with bioburden rather than a water-based product.
- Using two different chemical formulations together to clean and disinfect, such as a water-based phenol to clean, followed by a peroxide, bleach, quaternary ammonium, or alcohol product to disinfect.
- Leaving lids open on canisters, letting wipes dry out.
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