SURFACE SANITATION VERIFICATION
PURPOSE:
The primary purpose of this information paper is to provide guidance on the use and implementation of the Charm PocketSwab( for surface sanitation verification in commissaries located throughout EUCOM.
BACKGROUND:
ATP (adenosine triphosphate) bioluminescence has been used in the food industry for over 10 years to quickly assess and monitor microbial contamination on surfaces. ATP is an excellent means of identifying “hot spots” or areas with organic material that could possibly support and accelerate microbial growth. The technology of ATP bioluminescence for hygiene monitoring has become increasingly useful because of it real-time capabilities, ease of use and affordability. It cannot replace microbiological testing but it is easier, faster and the results indicate cleanliness, (defined as the absence of organic material), rather than counting colony forming units of microorganisms.
SCIENTIFIC PRINCIPLE:
It is important to understand the basic principles of ATP bioluminescence. ATP is a molecule that is essential and common to all plant, animal and microbial cells. This compound combines and reacts with an enzyme (luciferase) resulting in the release of light. The light emitted is measured by using the Charm LUM-T. This output of light is proportional to the amount of ATP present on a given surface. The measurement of biological contamination is approximated by determining the amount of ATP contained within or on the material. The sample collected is typically a 4-inch square area (100 cm2) that has been swabbed with a PocketSwab(. For reproducibility and consistency from one inspector to the next, it is imperative that the surface area covered with the swab is standardized. The ATP is then extracted from the swab material and mixed with luciferin/luciferase. It is the combination between the luciferase and the ATP that initiates the light-generating reaction that is then measured in the form of RLUs (Relative Light Units). The resulting number is a measure of the amount of ATP on the surface tested and indicates surface cleanliness. It is NOT a bacterial count.
LIMITATIONS:
ATP bioluminescence is a non-specific test in which there are some limitations. Since it is a broad hygiene monitoring system, it not only detects bacteria but it also detects all other biological ATP present. Although it cannot specify between different sources from which ATP is being measured, it quickly gives feedback that the surface you are testing is or is not clean. There is no direct correlation between microbial counts and the amount of ATP on a surface. However, generally speaking, Charm readings of (5,000 are not associated with the presence of microorganisms. Charm readings (50,000 are almost always associated with the presence of microorganisms, particularly readings (100,000. The “gray area” falls between readings of 5,000 and 50,000. Sometimes readings in this range are associated with the presence of microorganisms and sometimes the readings are not. Again, these numbers are general and based on previous experience. The bottom line is that if ATP is present, whether from microorganisms or other biological material, then there is the potential for microbial growth.
IMPLEMENTATION:
The first step in utilizing the PocketSwab( as a tool to verify surface sanitation is to determine a baseline or the background ATP on the surface to be evaluated. This can be accomplished by testing the surface after YOU have rigorously cleaned and sanitized the surface. By doing this, you know exactly how clean that surface can be and this will help to establish your baseline. Generally, clean surfaces will show very low levels of total ATP. Due to the fact the PocketSwab is very sensitive, a threshold of 10 times background can be accepted. For example, you have cleaned and sanitized a surface properly and you obtain a reading of 200. The acceptable threshold for a pass/fail would be 200 x 10 = 2,000. Different surfaces may, and probably will, have different pass/fail thresholds. That is why it is vital to establish a realistic, meaningful baseline during the implementation phase. The second step in utilizing the PocketSwab( to verify surface sanitation is to identify which surfaces to monitor. Obviously food contact surfaces are extremely important. Having said that, non-food contact surfaces are also important (e.g. floor drains). I recommend beginning with food contact surfaces and then expanding to other non-food contact surfaces.
MONITORING:
In order to have a value-added surface sanitation verification program, it is important to evaluate surfaces prior to the beginning of production on a routine basis. Daily surface sanitation verification is certainly best but that is not always feasible. Monitoring surfaces at least 2-3 times/week is acceptable. It is important to educate personnel on proper cleaning/sanitizing procedures in the area that you are monitoring. When routine monitoring produces results that are unacceptable, discuss the problem with the manager and initiate corrective action (e.g., clean and sanitize the equipment again prior to the start of production).
CONCLUSION:
The PocketSwab( gives a measurement of total ATP on a surface and it is a very sensitive method for surface sanitation verification. This should be kept in mind when comparing Charm readings with the results of conventional methods. A surface may not contain microorganisms, but if it is contaminated with any biological materials (as indicated by the presence of ATP) it could potentially provide for rapid growth of microorganisms. This source of contamination is detected by the ATP test but is missed by traditional microbiological methods. Any questions or requests for assistance/training can be addressed to MAJ Beach, Chief, Food Analysis Department, Vet Lab Europe.