Regulatory and Environmental Consulting
SPECIFIC RISKS IN A HEALTH CARE FACILITY
Five to six percent of hospitalized patients in the United States develop nosocomial infections. A nosocomial infection is one that occurs after a patient has been hospitalized or admitted to a health care facility or after a routine visit to a doctor’s or dentist’s office.
These infections happen as a result of pathogenic bacteria which are present within the facility, being transferred to a susceptible individual with a low resistance towards the bacteria. Infections can occur through the following routes:
By Direct Contact:
A person who touches the skin of another person with an infection is susceptible to develop that infection.
By Indirect Contact:
This occurs as a result of the transmission of infectious bacteria through improperly disinfected or sterilized medical instruments, patient care equipment or through the hands of health care workers.
By Airborne Transmission:
Infectious bacteria can readily become airborne. Coughing and sneezing produces fine aerosol sized droplets which are often projected 3 to 6 feet away from the source and can remain airborne for a considerable period of time. By breathing potentially infectious air individuals near by are at a high risk of acquiring the infections themselves.
Pathogenic bacteria - which may be present on environmental surfaces, as a result of improper cleaning or removal of gross soils - can become airborne and carried on dust particle. They tend to remain afloat for many hours and travel over long distances within the health care facility, putting patients and personnel at risk.
The major causes of nosocomial
infections are either due to ineffective cleaning of environmental surfaces
or inadequate disinfection of medical devices. This article will address
the issues of cleaning and disinfection of surfaces which are encountered
in a health care facility.
Types of Surfaces Which
Require Cleaning and Disinfection
Usually, several protocols are in place for cleaning and disinfection, based on whether the surface being disinfected is an environmental one or pertains to medical equipment and devices.
These surfaces include floors, walls and table tops; they are not considered high risk sources for the transmission of infections, unless they are grossly contaminated. A detergent with or without a low-level disinfectant is sufficient for routine cleaning, which should be done on a regular schedule. The neutral-based detergent used, should have sufficient cleaning power to dissolve and emulsify oil-based and proteinaceous soils. Detergent solutions which are used for routine cleaning need to be free-rinsing and easily removed from an environmental surface with a wet mop, sponge or cloth.
However, when an environmental surface however, is significantly contaminated with blood or other potentially infectious fluids, these contaminants must be thoroughly cleaned from the surface followed by the application of an intermediate-level disinfectant.
Types of Medical Surfaces:
Medical Surfaces include surfaces on Medical Equipment and Medical Devices
Medical Equipment Surfaces
Medical equipment surfaces such as switches on patient monitoring equipment, can potentially play a role in the transmission of infectious diseases. Although these surfaces do not come into direct contact with patients, they may become contaminated via the hands of health care personnel. Personnel who touch the contaminated surfaces may transmit microorganisms by touching other patients.
For sensitive equipment, biological contamination can be readily removed with a sponge or cloth which has been soaked in a neutral detergent solution. Biological fluids often contain high levels of calcium, magnesium and iron which can interfere with over all detergency. For this reason, Hospital Grade Cleaners should contain high concentrations of sequesterants such as sodium EDTA in order to tie up these interfering ions. The end result is an increase in the efficiency of the cleaning process, and the elimination of stains or streaks which would otherwise result.
After cleaning medical equipment, surfaces should be disinfected with an intermediate level-disinfectant.
Medical Devices Surfaces:
These surfaces can be classified into 3 categories and the level of disinfection required for each item will depend on its application. For a review and definition of the different levels of disinfection; high-level disinfection (HLD), intermediate- level disinfection (ILD) and low-level disinfection (LLD), please consult the article on “Choosing the Proper Sanitizer or Disinfectant”, by Nathan Schiff, Ph.D. which was published in the September, 1998 issue of MAINTENANCE SUPPLIES.
Regardless of the device being disinfected or the level of disinfection required, cleaning with a detergent must precede before effective disinfection can occur. The devices are then allowed to soak in a disinfectant solution for 20 minutes to several hours. Following disinfection, the surfaces are usually rinsed with sterile or high quality water containing very low levels of inherent micro organism.
Types of Devices Requiring Disinfection
These devices are the ones which come into contact with intact skin but not with mucous membranes an example of which is a blood pressure cuff. Low-level disinfection, achieve with quats, would be adequate.
These devices are the ones which come into contact with mucous
membranes and broken skin, such as respiratory therapy equipment and endoscopes. Most of these items require high-level disinfection.
However, some semi-critical items such as hydrotherapy tanks may
require only intermediate level disinfection, after a risk assessment of their potential disease transmission capabilities has been evaluated.
These devices which are designed to enter sterile tissue, such as surgical instruments and cardiac catheters or are to be inserted into arteries and veins must be sterilized prior to their reuse.
C. METHODS OF MICROBIAL CONTROL IN A HEALTH CARE FACILITY
Sterilization is a process in which all forms of microbial life, including spores, are destroyed. Its use is limited to those instruments or devices that penetrate skin such as scalpels. The most common ways of achieving sterilization are through autoclaving or exposure to ethylene oxide gas.
Autoclaving is a method of sterilization in which items are exposed to moist heat for 20 minutes at a temperature of 250 F (121 C) and under a pressure of 15 psi. Autoclaving is used under conditions in which high temperature exposure will not damage the items being sterilized. Because proper sterilization is a very critical procedure, a strip containing spores (Bacillus stearothermophilis) is often placed along with other items to be sterilized, to act as a check for spore killing effectiveness. The strip is then placed into spore germination media, to determine if the spores have been killed.
Ethylene oxide gas
Ethylene oxide gas reacts with bacteria and spores and inactivates them. The items are generally exposed to ethylene oxide gas for 2 to 3 hours at 140 F
(60 C) and under a pressure of 12-15 psi. It is absolutely essential to ventilate the items in a sterile environment for several hours after exposure in order to eliminate all traces of ethylene oxide gas.
The main advantage in using ethylene oxide for sterilization is that it can be used on heat-sensitive materials, including certain surgical items or sensitive plastics.
Disinfectants are a category of chemicals that can kill pathogenic microorganisms to various degrees. They fall into three categories:
1. Low-level disinfectants
2. Intermediate-level disinfectants (ILD)
3. High-level disinfectants (HLD).
Depending on the type of microorganism, effectiveness can be limited by such factors as: water hardness, pH, temperature and freshness of the soil load. EPA Approved hospital disinfectants are designed to be effective at the manufacturers stated concentration.
Disinfectants are always applied after cleaning a surface and rinsing it with potable water. The disinfectant solution is generally applied to the surface for a period of at least 10 minutes and the surface is allowed to remain wet during the interval. Following disinfection, the surface is usually rinsed with sterile water or high quality potable water, in order not to recontaminate the equipment.
Table 1 summarizes the types of chemical disinfectants and the degree of disinfection for which they are recommended.
Quaternary Ammonium Compound
Quats are effective against a broad spectrum of microorganisms. Quats can be used directly as disinfectants or can be combined with synthetic detergents, that allows them to be used also as disinfectant-cleaners. These type of disinfectants are mainly used in routine cleaning or in one-step cleaning and disinfection procedures.
For straight disinfection, modern, third generation Hospital Grade quats consists of a blend of four different quaternary ammonium chloride compounds, manufactured to a specified level of total active germicidal ingredients. The trend in many health care facilities is to use a 10% active product, however, where cost is a major concern, a 5% quat is used, but at a higher concentration.
A typical quat disinfectant-detergent contains 4.5% quat. It is used in a one-step cleaning and disinfection procedure. However, the use of disinfectant-detergent blends is not recommended on high traffic floor areas, since rinsing away the excess product off the floor may be difficult and time consuming, thereby posing a potential risk of the floor becoming slippery.
Peroxyacetic Acid (PAA)
PAA is an exceptional product which functions as a HLD and sterilant when applied at 250 to 300 ppm. Some of the advantages of PAA are:
1. it exerts biocidal activity
2. it is effective in the presence of some organic matter
3. it is also sporicidal at ambient and low temperatures.
Currently PAA is used for in many hospitals for sterilizing surfaces requiring HLD. PAA solutions exert optimal biocidal activity in the pH range of 3.5 - 5.5. In general, PAA should not be used in the presence of alkaline soils or on unsealed porous surfaces, since doing so will neutralize the PAA, rendering it ineffective as a disinfectant.
For routine sanitization, hypochlorites are used at 200 ppm available chlorine. For LLD a minimum of 500 ppm available chlorine is required and for ILD disinfection, at least 1000 ppm of available chlorine is required. The activity of hypochlorites are greatly affected by water hardness and pH. At high pH, available chlorine or hypochlorous acid (the germicidal component of hypochlorites), is present in very low concentrations resulting in prolonged disinfection times and lower levels of disinfection. Hypochlorites also degrade with age and should be tested frequently in order to provide consistent results.
Glutaraldehyde is considered to be a HLD and is used mainly to disinfect critical items at a very high level of disinfection. The recommended exposure time for cold sterilization is 3 to 10 hours. Care must be taken in handling glutaraldehyde because of it’s low STEL (short term exposure limit) of 10 minutes at 0.2 ppm.
Phenolics are considered to be ILD and their main value, is in their capability of destroying TB causing bacteria. Another advantage of using phenolics is their ability to tolerate moderate loads of organic contamination without a loss in their germicidal activity. They are generally used at 500 ppm of active chlorinated phenol.
However the use of phenolics poses certain disadvantages.
Phenolics have a tendency to be absorbed by rubber and by some plastics and therefore can not be used on all surfaces.
Iodophors attach themselves to vital bacterial proteins and inactivate them. Hospital-grade iodophors consist of elemental iodine which is compelled to a carrier such as PVP (polyvinylpyrolidone) and referred to as PVP-Iodine The carrier provides a sustained-release reservoir of iodine as needed, to maintain a given concentration of iodine in solution.
For disinfection or disinfection-cleaning
in a health care facility, iodophors are generally used at a concentration
that will provide 75 ppm of available iodine.
Iodine solutions also function at a low pH, and for this reason also facilitate the removal of hard water deposits from surfaces. Their main disadvantage is that they can be highly staining on virtually any surface, work well only within the acidic pH range and flash off at temperatures greater that 100 F ( 38 C). The main application of iodophors in a health care facility is in their use in topical applications and as germicidal hand cleansers and germicidal hand dips.
D. Germicidal Hand Cleaners
Hand washing is generally considered to be the single most important procedure for preventing nosocomial infections. Hospital personnel and health care providers are believed to be the mode of transmission for most preventable infections. Hand washing has been shown to eliminate or markedly reduce the hand transfer of pathogenic organisms.
Germicidal hand cleansers are designed for the rapid removal and elimination of transient skin microorganisms. The most commonly used active ingredients in germicidal hand cleansers are and triclosan (up to 1%) and para-chloro-meta-xylenol or pcmx (0.24% - 3.75%); but typical products contain 0.5% triclosan or 1.75% pcmx. Pcmx is more effective in destroying pseudomonas bacteria, but at a higher concentration than that permitted for triclosan.
The trend in germicidal hand cleansers is towards low irritating product, using mild surfactants, emollients and moisturizers. These products are also designed for very frequent use, up to 50 times per day. Residual or persistent germicidal activity is desirable, but not a mandatory characteristic of these product, due to their frequency of use.
Unlike a germicidal hand cleanser, a surgical scrub is defined as an antiseptic containing preparation which not only significantly reduces the number of microorganisms on the skin, but also has residual or persistent antimicrobial activity. Surgical scrubs are also used for topical skin applications prior to surgery. They can also be used for hand cleansing usually contain chlorhexidine gluconate (4%).
Delivery of germicidal hand
cleansers in a health care facility is usually done through foot or thigh
activated pumps or by depressing a plunger pump which is built into the
packaging unit. In essence, fresh product is provided with each stroke
and cross contamination, as has been shown to occur with bar soap, is eliminated.
METHODS AND TIME REQUIREMENTS COMPARISONS FOR THE DIFFERENT DISINFECTION CATEGORIES
Time in Minutes Required for Disinfection
Method of Disinfection
Dosage Required (ppm)
120 - 180
120 - 180
120 - 180
180 - 600
250 - 300
Less than 1 min.
500 - 750
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