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Golden Rule: Cleaning Must Precede Sterilization

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Golden Rule: Cleaning Must Precede Sterilization
By Nicole Kenny, Virox Technologies Inc.

Much of the literature on disinfectants and sterilants opens with a definition of terms. Which indicates that the subject is not a simple one, although it can be understood with a little effort. William A. Rutala, PhD, MPH, University of North Carolina at Chapel Hill, a world-renowned expert on the subject, describes sterilization as “the complete elimination or destruction of all forms of microbial life, required for instruments or devices that have contact with sterile tissue. Disinfection describes a process that eliminates many or all pathogenic microorganisms on inanimate objects with the exception of bacterial spores.” Therefore, chemicals that eliminate all microbial life, including spores, are referred to as sterilants, whereas disinfectants eliminate all or most pathogenic organisms but not spores.

The Importance Of Pre-cleaning
Before objects are disinfected or sterilized, they must be rendered safe to handle, so first they must be decontaminated. In fact, the most important step toward disinfection or sterilization is a thorough cleaning of the objects. And, while cleaning does help reduce the microbial load, its real purpose is to remove soil such as blood, pus or mucous that would interfere with the disinfectant or sterilant in doing its job by blocking direct contact to the object. “Cleaning is the removal of foreign material (e.g. soil and organic material) from objects,” Rutala said, “and it is normally accomplished using water with detergents or enzymatic products. Thorough cleaning is required before high-level disinfection and sterilization since inorganic and organic materials that remain on the surfaces of instruments interfere with the effectiveness of these processes.”

The most oft-repeated phrase in the industry is, “If it’s not clean, you can’t sterilize it.” That sounds a little funny, but it’s really very serious. As long as there is bioburden on an instrument, no matter how miniscule, the instrument is unsafe to use and can cause cross-contamination.

Bioburden that is not cleaned from instruments before disinfection or sterilization can translate to added costs due to cross-contamination, which can lead to lengthier hospital stays and further treatments for patients, but it also can shorten the life of the instrument unnecessarily, causing the need for repairs or early replacement. Residual bioburden can cause harmful corrosion, rusting and pitting, reducing the life of the instrument. That is why it is important to remove all bio-burden (blood, fat, carbohydrates, starch and protein). If you have an enzymatic cleaner containing only a protein enzyme, you are not going to be able to remove fat, carbohydrates or starch; so, you must have a pre-cleaner to remove each contaminant: carbohydrates, starch, blood, protein and fat.

Factors To Consider When Choosing Disinfectants
Disinfectants and sterilants should be selected carefully, with consideration given to the type of material out of which the instrument or item to be disinfected or sterilized is made. For instance, heat is one of the suggestions for sterilizing critical items, but the item must be able to tolerate the heat or it could be minded. Clearly, it’s important to have a knowledge of which chemicals are appropriate to use on which materials. Manufacturer’s recommendations must be given serious consideration.

Some of the chemicals cross categories, the difference being the level of disinfection, which is determine by the length of time the object is exposed to the chemical. For example, some disinfectants will kill spores, sterilizing objects, if the objects are exposed to the chemicals for an extended period of time. These same disinfectants, at different concentrations and at shorter periods of exposure, will perform high-level disinfection by killing all microorganisms except high numbers of bacterial spores. Which disinfectant is chosen, the concentration of the disinfectant, and the exposure time is determined by the risk of infection posed with the use of the instrument or item.

Properties Of Ideal Disinfectants
Disinfectants should be a broad-spectrum antimicrobial, be fast-acting, be unaffected by environmental factors, be non-toxic, by surface-compatible so that it doesn’t cause corroding or deterioration, be easy to use, be odourless, be economical, be water-soluble, be stable in concentrate and use-dilution, have good cleaning properties, be non-flammable.

An interesting point is that certain organisms seem to have a built-in resistance to certain disinfectants that leave an active residue. In some cases the concentration of the chemical can make a difference in the organisms’ susceptibility to the disinfectant.

There’s a great deal about which one must be educated when in charge of choosing chemicals and methods used to sterilize or disinfect items reused on or by patients, much that’s really important to understand before it’s possible to make informed and responsible choices. But there is one thing that isn’t understood, and, oddly enough, that’s how sterilants and disinfectants work. “The mechanisms by which germicides inactivate microorganisms remain incompletely understood,” said Rutala. “Unlike antibiotics, most disinfectants have multiple target sites of action to include the cell wall, cytoplasmic membranes, and cytoplasmic constituents (e.g. nucleic acids, ribosomes, etc.).”

We can live without complete knowledge of how disinfectants work. Fortunately, strict adherence to using them properly makes that possible for many people each day.