1. When reading the new provincial infection control guidelines I see terms referring to different classes of treatment devices and instruments. What exactly do they mean?
A number of years ago, the Centers for Disease Control and Prevention (CDC) modified and updated the original Spaulding classification scheme for patient-care items. These categories termed, critical, semi-critical, and non-critical, were first developed by Spaulding in 1968 when he considered strategies for disinfecting and sterilizing medical and surgical instruments. Dental instruments, devices, and equipment were included in later revisions. This Spaulding classification continues to be used in infection control recommendations and guidelines. The categories are:
Critical items such as surgical instruments, periodontal scalers, and scalpels used to penetrate soft tissue or bone have the greatest risk of transmitting infection and should be cleaned and sterilized by heat.
Semi-criticial items touch mucous membranes or non-intact skin and have a lower risk of transmission, but because semi-critical items in dentistry are heat-tolerant, they should also by sterilized by using heat. Dental examples here include mouth mirrors, handpieces, amalgam condensers, and reusable impression trays. If a semi-critical item is heat-sensitive, it should at a minimum be processed with a high-level disinfectant.
Noncritical patient-care items pose the least risk of infection transmission, contacting only intact skin. In most cases, cleaning, or if the item is visibly soiled, cleaning followed by disinfection is adequate. The recently approved dental infection control recommendations for Alberta call for cleaning and disinfection with an intermediate-level disinfectant, that is a hospital-level disinfectant (low-level) with an additional tuberculocidal claim. The guidelines published by the Royal College of Dental Surgeons of Ontario recommend cleaning and subsequent use of a low-level disinfectant only.
2. What is the difference between the various types of chemical indicators?
Chemical indicators use sensitive chemicals to assess physical conditions (e.g. time and temperature) during the sterilization process. Common forms of these indicators include paper strips, labels, and steam pattern cards. Because chemical indicators do not contain bacterial spores, they do not prove that sterilization has been achieved. They do, however, allow detection of certain equipment malfunctions and can help identify procedural errors. External indicators applied to the outside of the package can verify that the package has been exposed to the sterilization process. However, some external indicators change color long before appropriate sterilization conditions have even been reached. Autoclave tape is an example of this kind of indicator. External indicators are primarily used to identify packages that have been processed through a heat sterilizer, thus preventing the accidental use of unprocessed items. Recommendations include the use of an internal chemical indicator inside each package to evaluate whether the instruments were exposed to the sterilization conditions. In other words, internal chemical indicators are used to ensure that the sterilizing agent has penetrated the packaging material and actually reached the instruments.
3. What are the most common reasons for sterilization failure using a heat sterilizer?
a. Inadequate precleaning of instruments
b. Improper maintenance of equipment
c. Cycle time too short or temperature too low
d. Overloading or improper loading of sterilizer chamber
e. Incompatible packaging material
f. Interruption of sterilization cycle to add or remove an item. Multiple investigations have found that the most frequent cause of sterilization failure in human error.
4. What should a proper hand washing agent be expected to accomplish?
At a minimum it should: 1) provide good mechanical cleansing of skin; 2) have the capacity to kill a variety of microorganisms if is used in a surgical settings; 3) have some residual antimicrobial effect to prevent re-growth of resident bacteria and fungi when used for surgical hand washing; and 4) be dispensed in a manner without risk of cross-contamination among HCW. The major concern is the presence of transient flora on the person’s hands. The goal is to wash off the flora, killing them with an anti-microbial agent is supplemental.
5. What needle-recapping devices are acceptable?
Any recapping must be done with a mechanical device or a technique that uses only one hand (i.e. scoop technique). Such techniques ensure that needles are never pointed at or moved toward the practicing HCW, patient, or other workers, either on purpose or accidentally. Newer, self- sheathing anesthetic syringes and needle devices are available and do not require any movements associated with recapping.
6. What are the two types of hypersensitivity reactions associated with latex gloves and latex items?
Type I hypersensitivity is an immediate hypersensitivity which typically develops within a few minutes after an allergic person either comes into direct contact with allergens via tissues or mucous membranes, such as when donning latex gloves, or is exposed via aerosolization of latex protein allergens. A wheal and flare reaction (ie. cutaneous anaphylactic reaction, urticaria, hives) may develop along with itching and localized edema. Coughing, wheezing, shortness of breath, and/or respiratory distress can occur, depending on the person’s extent of sensitization. Systemic Type I hypersensitivity can also be life-threatening and cause anaphylactic shock. Type IV latex hypersensitivity is a delayed immunological response, most often manifested as a contact dermatitis. It is characterized by a several hour delay in symptoms and a lymphocytic reaction that peaks in 24-48 hours. The slow-forming, chronic inflammatory reaction is well demarcated on the skin and is surrounded by localized edema. Healing of the lesion may take up to 4 days with scabbing and sloughing of affected epithelial areas.
7. What is the difference between sterilization and disinfection?
Sterilization is the destruction or removal of all forms of life, with particular reference to microbial organisms. The limiting factor and requirement for sterilization is the destruction of heat-resistant bacterial and mycotic spores. Disinfection is the destruction of pathogenic and other kinds of microorganisms by physical or chemical means. Disinfection is less lethal than sterilization because it destroys most recognized pathogenic microorganisms, but not necessarily all microbial forms, such as bacterial spores. Disinfection does not ensure the margin of safety associated with sterilization processes.
8. Does environmental surface infection control consider all surfaces as equal, and must they be treated the same between patient appointments?
First of all, environmental surfaces are classified as non-critical items, which means there is a relatively low risk of disease transmission from most contaminated surfaces. There are two categories of environmental surfaces: clinical contact surfaces and housekeeping surfaces. These require different infection control practices based on the potential for direct patient contact, degree and frequency of hand contact, and potential contamination of the surface with body substances or pathogens. Clinical contact surfaces are defined as surfaces that act as reservoirs for microbial contaminats with the potential to transmit infection, because they can be directly contaminated from patient materials either by direct spray or spatter or by (gloved) hand or instrument contact. Examples include light handles, switches, dental chairside computers, telephones, and countertops. These surfaces should be covered with disposable single-use barriers to prev
ent contamination, or cleaned and disinfected with a a low-to-intermediate (e.g. tuberculocidal) level disinfectant. In contrast, housekeeping surfaces, such as floors, walls, and sinks, have limited risk of disease transmission because they are not involved in direct delivery of patient care. They can be cleaned only and do not routinely require disinfection.
9. Should a disinfectant be used as a holding solution?
No. it is not necessary. The purpose of a holding solution is to keep debris moist on hand instruments until they can be cleaned and sterilized. Holding solutions are not intended to disinfect or sterilize. Presoaking in a disinfectant does not accomplish, much if any, disinfection; it adds unnecessary time and the extra expense of disinfectant use. After presoaking, items still need to be cleaned, wrapped, and heat-sterilized before use in patient care.
10. What are major considerations for hand hygiene?
Multiple factors must be evaluated and the best approaches implemented in order to make this important infection control area as effective as possible for protection of the HCW. These include:
a. consider skin sensitivities and allergies of personnel when selecting products;
b. initial procedure at the beginning of the day should include a thorough hand wash;
c. use appropriate hand washing and rinsing techniques, with particular attention to thumbs and fingertips;
d. subsequent hand hygiene procedures should last approximately 15 seconds or the time recommended for the specific preparation;
e. alcohol-based hand rubs can be used as effective alternatives for hand washing on clean hands;
f. do not wear jewelry or long nails;
g. clean thoroughly under nails;
h. when washing hands, rinse with cool or tepid water and dry completely before donning gloves;
i. keep epithelial integrity intact.
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John A. Molinari, Ph.D, Director of Infection Control, THE DENTAL ADVISOR, Ann Arbor, MI.
Oral Health welcomes this original article.
