There are three reasons that cause bacteria to become resistant against commercial available sanitizing or disinfecting products.
a. RESISTANT BACTERIA AND SUB-LETHAL SANITIZER DOSAGE
In any given population, bacteria exist within a wide range of sensitivities towards a specific sanitizer dose. Under normal conditions of exposure, sanitizers are capable of destroying 99.999% of the bacteria present. In essence, a surface which initially harbor 1,000,000 bacteria per square centimeter prior to sanitation may be expected to contain only 10 microorganisms per square centimeter afterwards. In such a scenario, the objective of the sanitation process has been achieved in the sense that the total bacterial population has been reduced to safe levels.
What may not be as evident is that the remaining 10 surviving microorganisms capable of withstanding the sanitization procedure, have the potential to act as a source of future contamination. If on subsequent clean up and sanitization, proper dosing or procedures were not adhered to, or the surface has not been adequately rinsed, the 10 surviving bacteria will survive a second cycle of sanitization, as will other bacteria. Over a period of time and involving several cleaning and sanitization cycles, the resistant survivors have the capacity to proliferate, especially during periods in which they are exposed to food product. When this occurs the food processing plant is now dealing with a bacterial population which no longer responds to sanitizing doses of germicide, resulting in a failure of the sanitizer to achieve its objectives. In essence by applying the sanitizer at less than lethal doses or for shorter intervals, the end result is the same as if selective culturing of a resistant strain had been carried out with the possibility of the surface becoming enriched with pathogens and hard-to-kill microorganisms.
A surface which is allowed to deteriorate to such a level of poor hygiene, needs to be “shocked”, by switching to high doses of an alternate product such as hypochlorite and dosing at disinfectant levels. It is not uncommon to require the use 400+ ppm of available chlorine over a period of a week before the surface can be returned to the desirable and bacterial free state.
b. BIOFILM FORMATION
Biofilm formation is another mechanism, in which bacterial resistance towards a sanitizer can occur. As previously indicated, proper cleaning is essential before effective sanitization can occur. Certain bacteria, secrete a polysaccharide which is a constituent of their membrane. These secretions are very sticky and attach themselves firmly to metal surface. The resulting film so formed containing trapped bacteria is referred to as a biofilm. Bacteria which are responsible for biofilm formation may in themselves not be harmful or pathogenic. However, the gelatinous matrix which they excrete is capable of attracting to itself and embedding pathogenic bacteria, such as Lysteria monocytogenes. Although the pathogens themselves do not contribute towards the integrity of the film, they nevertheless are capable of contaminating products which come into contact with the surface.
Biofilms are often very difficult to remove, since their matrix is very resistant to chemical attack by detergents. They often require higher than normal concentrations of alkaline detergents and strong oxidizing levels of sodium hypochlorite in order to remove them. Several applications may be required before the biofilm can be totally removed.
c. DETERGENT-SANITIZER INTERACTIONS
Most cleaning products contain either non-ionic surfactants (emulsifiers and detergents), anionic surfactants or a mixture of both in their composition. In solution, non ionic surfactants are electrically neutral, but anionic surfactants carry a negative charge within their structure. When detergent is applied to a soiled vertical surface the bulk of product runs of within 15 to 20 minutes. However, a small but finite amount of detergent remains on the surface and contains some of the anionic surfactant which was present in solution originally applied to the surface. If the surface is not thoroughly rinsed prior to the application of a quat sanitizer, the sanitizer can be totally inactivated. In solution, quats are positively charged and can therefore combine readily with the negatively charged anionic residue and become totally inactivated.
A metering system may be set to deliver the correct concentration of quat (200 ppm), but once the sanitizer comes into contact with the surface, it reacts with the anionic detergent, and the resulting anionic-quat residue or film so formed has no germicidal activity. Since an anionic-quat complex so formed also contains nutrients favoring microbial growth. Such a complex can actually support bacterial proliferation if left unchecked.
Neutral Electrolyzed Water (NEW) is a strong oxidizer with hypochlorous acid (HOCL) as active ingredient. HOCL has superior germicidal properties compared to commercial available products. Moreover, as NEW has a very high oxidation-reduction potential (ORP), microorganisms are effectively and 100.00% destroyed. ORP reactions at the cell membrane are the main cause that microbial cells cannot defend themselves when exposed to NEW. Once ORP-reaction have weakened the cell membrane, HOCL is able to penetrate cells and destroy the microorganisms from inside. The last 25 years, a lot of research has been done to explain the superior biocidal activity of NEW. Most scientist believe that ORP reactions, dissolved chlorine (HOCL) and oxygen are the main reasons for NEW’s superiority. Up to now, not a single occurence has been discovered whereas bacteria were able to become resistant against NEW. It is therefore that scientist who studied the unique features of NEW are convinced that NEW IS the answer to combat hard-to-kill organisms.
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