Clarification on the difference between Protein Residue Testing and an ATP test; The two infection control processes
The following comparative analysis was recently published by Terragene® to clarify the difference between Protein Residue Testing Vs ATP, to end the confusion spread within the healthcare sector about Swab techniques and the HTM01-01:2016 requirements.
What is an ATP test?
To start with, it is necessary to explain that an ATP test was born to serve a specific purpose in the food industry market, such as to monitor microbiological contaminations after disinfection of the surfaces and machines. After this, and as a consequence of healthcare-acquired infections (HAIs) outbreaks a few decades ago, hospitals started to perceive that they need to incorporate a similar control inside the CSSD.
Since there was no better technology or testing method available rather than ATP at that time, both hospital’s urge and the manufacturer’s smartness, led the market to incorporate this testing method inside hospitals. But let’s make this clear… this was a mistake. And below a list of reasons why: the main objective of a washing/cleaning process in hospitals is to eliminate blood and tissue remains, thus guaranteeing that subsequent disinfection and sterilization processes will be successful.
Nowadays, the main challenge that washer and detergent manufacturers face, is the complete removal of proteins from reprocessed instruments. Thus, if we are talking about a test for cleaning effectiveness, protein should be the chosen one. The same is true for sterilization, if we want to corroborate complete elimination of microorganisms, we have to use a BI with bacterial spores (the most resistant form of life with prions) to do this monitoring. In this sense, blood and tissue residues consist of both cells and proteins.
The most difficult to remove are the proteins that coagulate and adhere to the instruments, making the washing process very difficult to accomplish successfully. So, why bothering to measure ATP levels if instruments will subsequently be exposed to a sterilization process to remove any living cell remaining? This leaves ATP restricted to surface disinfection control in food industry rather than inside the CSSD.
ATP does not represent contamination itself, so microbial or organic contamination will always be an indirect measure (when measured by ATP). On the other hand, protein residues do represent a direct measure of organic/microbial contamination. Not only this but more importantly, proteins are the most difficult to remove residues during a cleaning process. For this reason, if we are talking about cleaning effectiveness, protein testing is undoubtedly the best marker.
ATP is a very easy to hydrolyse molecule, so it does not represent a challenge to the washing procedure. In this sense, hospital washing/cleaning parameters do guarantee that any ATP molecule will be destroyed during the process (temperature, detergents or disinfectants, etc). Not only this but if there is any chance that ATP molecules remain after the washing cycle, free ATP will inevitably hydrolyse within a few minutes. Consequently, it is very unlikely that an ATP test will give a positive result after a hospital washing cycle.
It has been proved that some ATP tests fail to lyse some bacterial cells, thus liberation of ATP inside them for the subsequent ATP measuring could be compromised (if we consider ATP as microbial testing). Again, for instruments that will undergo a sterilization process after cleaning/disinfection, there is no meaning to test for bacterial contamination. It has also been shown that some detergents and disinfectants used in hospitals interfere with the bioluminescence reaction. ATP is not present in viruses and, more importantly nowadays, in Prions, protein infectious agents.
Comparative Analysis Betwwen Protein Residue Testing & ATP Test
Composed entirely of a protein material that causes transmissible spongiform encephalopathies, such as variant Creutzfeldt-Jakob disease. Remarkably, proteins are one of the main components of viruses, while prions actually are infectious proteins themselves. The relevance of this issue is such that institutions such as the UK Department of Health have set limits on micrograms ( g) of protein to consider an instrument as “clean” in The Health Technical Memorandum 01-01 (HTM 01-01). Therefore, it is not enough with the simple detection of proteins, but also its quantification by electronic systems of high sensitivity and temporary analysis of the evaluated samples is important.
Chemdye® PRO1 MICRO represents an easy option to monitor the cleaning of reusable medical devices in the context of medical, dental practices and industry from the detection and quantification of surface proteins, allergens and reducing agents. The system consists of a swab of special characteristics and two reactive solutions contained in the same device. PRO1 MICRO offers a quantitative colorimetric result that can be quantified with high sensitivity using any of the Bionova® Auto-readers IC10/20FRLCD and MiniPro.
For the detection of microorganisms by means of ATP, the available systems are only similar to PRO1MICRO in its structure, but the biochemical reactions are very distant because they were developed for different purposes. ATP, the energy source of microorganisms, triggers a light reaction that can be measured in a Luminometer. This system does not recognize proteins of any nature. In conclusion, proteins do fulfil all the requirements to be the marker molecule for cleaning effectiveness monitoring, making our Chemdye® PRO1 MICRO system the most reliable cleaning monitoring system in the market.