t
INFECTION PREVENTION & CONTROL
Enzymatic and non-enzymatic detergents
There is a choice between using enzymatic or non-enzymatic detergents. Non-enzymatic detergents are effective within a wide temperature range, are less affected by variations in pH and less likely to trigger allergic reactions. However, non-enzymatic detergents are not as effective at cleaning either in the range of residues that can be removed or in the removal of stubborn residues. This is a drawback as the removal of soil with a strong surface attachment is important for the later disinfection step, so that the disinfectant can reach any remaining microorganisms.9 An enzymatic detergent is a class of cleaning agent which contains added enzymes – proteins consisting of long chain amino acids held together by peptide bonds. These enzymes are biocatalysts capable of accelerating the rate of reaction and digesting residual organic material fixed to the endoscope, such as blood and mucous which are formed of proteins, lipids, carbohydrates and various chemical bases. An enzymatic detergent breaks down larger molecules into smaller ones.10
This
transforms water insoluble matter into molecules that are water-soluble, which serves to keep the molecules in suspension and facilitates their removal.
Enzymatic cleaning solutions also use
surfactants to break down and suspend soil, then digest the released soil. Most surfactants act as wetting agents, lowering the surface tension of the cleaning solution. The residual compounds can then be rinsed off from the device, using filtered water with a low-starting bioburden. For this reason, enzymatic detergents are sometimes referred to as ‘double-cleaning’ agents. Enzymatic detergents have been demonstrated to be superior to non- enzymatic ones, when variables of time, temperature and staff practices are controlled, as evidenced through laboratory studies.11,12
This cleaning efficacy is also
dependent upon the types of enzymes included in the detergent formulation, and their demonstrated effectiveness, such as
When using enzymatic detergents there are important factors to note including health and safety precautions to observe.13
These factors
include the quality of water used, which is important, not only in terms of bioburden control, but also in relation to water hardness.
the inclusion of protease, which slices up proteins; carbohydrate digesting enzymes (such as amylase); and lipase, for the digestion of fats. In addition, there are enzymes that will target the insoluble polysaccharide outermost layer of a biofilm. Therefore, a detergent with a multi-tiered blend of enzymes should be selected, with the ability to work on traces of blood, carbohydrates, protein, polysaccharides, fats, oils, uric acid and other nitrogenous compounds, plus drug residues. A further consideration is the types of additional chemicals added to the formulation of the detergent, such as solubilising agents, soil-suspending agents, and surfactants with good wetting properties. These additives can help to enhance enzymatic action.
are important factors to note including health and safety precautions to observe.13
When using enzymatic detergents there These
factors include the quality of water used, which is important, not only in terms of
bioburden control, but also in relation to water hardness. Softened water is required since high levels of calcium and magnesium ions in water can elevate the pH, and decrease the effectivity of the enzymes (the effects of hard water can be partly overcome through the addition of sequestering agents to the detergent formulation).
Additional factors when using enzymatic detergents include ensuring the detergent is at the correct dilution (if required) and following the recommended time required for the enzymatic activity to take place, which should be incorporated into the cleaning process. A further factor concerns rinsing; if sufficiently high detergent residue remains on the internal and external surfaces of the endoscope, these residues may interfere with the action of the disinfectant. This risk can be mitigated by using pre-set rinse volumes or following set rinsing times. Further properties essential to an enzymatic detergent are for it to be non-abrasive, free rinsing and readily biodegradable. The production of most enzymes are from biological systems such as yeast, fungi and bacteria and the process is renewable, with a low environmental impact.14 It is also important to store enzymatic detergents correctly, as the effects of high heat and high humidity can disable enzymes, and thus degrade their cleaning ability. Most enzymatic detergents can be protected by storing them at room temperature and under low humidity conditions.15
Designing a safety protocol for enzymatic detergents
When used correctly, enzymatic detergents are more effective at removing soil than non-enzymatic detergents, but the risk of allergens and the potential impact on some healthcare workers requires effective
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