What is ATP?

ATP, or adenosine triphosphate, is where a cell gets its energy. Consisting of adenosine, an amino acid, and three phosphate groups. These phosphate groups in ATP have very high energy bonds that cells utilise for a vast majority of their processes. ATP is produced in the mitochondria of a cell from its less energetic ADP (adenosine diphosphate, 1 less phosphate group than ATP), and even less energetic AMP (adenosine monophosphate, 2 fewer phosphate groups than ATP).

ATP exists in the cell primarily in the cytosol; this ensures it’s readily available for organelles to use to fuel
its processes. Once used the energy (phosphate group) is used, ATP becomes ADP if 1 group is used (triphosphate to diphosphate). Processed through both the Krebs cycle and glycolysis (breaking down sugar), ATP is regenerated from ADP.

How To Interpret Adenosine Triphosphate (ATP) Test Results.

ATP production usually means that a cell is alive and undergoing metabolic processes. You may recall
the mnemonic MRS GREN describes what’s required for life: Movement, Respiration, Sensitivity,
Growth, Reproduction, Excretion, and Nutrition. Every process here relies on energy provided by ATP.
If a cell dies through apoptosis (programmed cell death), it will use up ATP as there are structured
processes to go through. If a cell dies through necrosis, it will not use ATP as an external factor that
has caused the cell to break down. As the cell begins to break down, it will release the cytosol and
organelles, so the ATP-rich cytosol, mitochondria, and nucleus are now available to measure. It has
also been shown that cells die with increased cytosolic ATP, and elevation of cytosolic ATP level is a
requisite to the apoptotic cell death process. NATURE ARTICLE.

Cytosolic ATP contains the most ATP out of any component of a cell. Therefore, it makes sense that,
by inducing cell death through strong oxidative processes such as contact with in situ peracetic acid (Peracide™), increased ATP levels are observed immediately after use.

What does this mean for ATP Testing?

Disinfectants cause a cell to die by necrosis. Therefore, an elevated level immediately after the use
of the disinfectant is expected. This means that the cell wall is broken; in other words, your disinfectant
is working.

ATP levels are not measurable in the case of viruses as they do not have mitochondria and therefore
do not have the capacity to create ATP.

In Summary:

ATP levels give an indication of the amount of extracellular ATP present on a surface. This measure
of energy doesn’t necessarily correlate to metabolic processes or the number of living cells on a
surface and particularly does not provide informative data when the cells are under stress. When in
contact with a high-level disinfectant, cells leak ATP in the mixture of degrading organelles. An initial
high reading means your disinfectant is working.

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Further reading and references:

1. Zamaraeva M, Sabirov R, Maeno E, Ando-Akatsuka Y, Bessonova S, Okada Y. Cells die with increased cytosolic ATP during apoptosis: a bioluminescence study with intracellular luciferase. https://nature.com/articles/4401661. 2022

2. [Internet]. https://www.pnas.org/doi/full/10.1073/pnas.0904764106. 2022 [cited 13 October 2022]. Available from: https://www.pnas.org/doi/full/10.1073/pnas.0904764106