ÆGIS Microbe Shield - Testing for Success

What is ATP testing

It is a very quick way to test surfaces.

The ATP test rapidly measures actively growing microorganisms through detection of adenosine triphosphate, or ATP.

ATP is the universal energy carrier found in all living organisms from the food we eat, our own body fluids and micro-organisms. The ATP content of foodstuff and body fluids is very large and is usually millions of times greater than that of micro-organisms. This is largely due to the size differences but is also a function of metabolic condition. ATP is a molecule found only in and around living cells, it gives a measure of biological concentration and health.

ATP is measured by the light produced through its reaction with the naturally-occurring firefly enzyme Luciferase using a Luminometer. The amount of light produced is directly proportional to the amount of biological energy present in the sample.

Some limitations of the ATP test

The correlation of detectable ATP as an indicator of live cells has been proven in numerous studies, however the following conditions impact the accuracy of ATP testing.

  • Dirt or soils which obscure sampled surfaces.
  • Biofilm made by colonised bacteria which shield cells from acquisition by swabbing.
  • Bacteria on surfaces that are not sampled by the swab.
  • Swab contact with live human cells from hands, or body fluids.
  • Presence of beneficial bacteria found in food production.

The ATP hygiene test detects ATP from all sources and cannot differentiate ATP from different sources. Contamination (organic matter or microbes) is not evenly distributed on a product’s contact surface. Accordingly, the ATP hygiene test should not be considered as an absolute, precise measurement of surface contamination. It is a sophisticated sensitive indicator test of hygienic status and potential risk. Is there a relationship between the ATP test result and microbial numbers on food production equipment? Yes, but it is a concurrent relationship. The primary purpose of cleaning is to remove product residue from product contact surfaces. Effective cleaning simultaneously removes the material capable of supporting microbial survival and growth, as well as many of the microbes themselves.

ATP tests are not intended to replace labortory based microbial tests but there is concurrent direct correlation between the results of the two methods. The ATP test is not suitable for the enumeration of microbes on contact surfaces because it does not have the desired sensitivity.

Microbial testing -  in a laboratory

A microbial test in a laboratory checks for the presence of microorganisms in a sample provided to the laboratory. This testing is used to confirm the presence of microorganisms.

In the case of ÆGIS Microbe Shield it is more likely that you wish to test the efficacy (success) of your treatment.

This may include sending two similar items to the lab one being treated with ÆGIS Microbe Shield and one not having been treated, this would be the control sample.

It may also include the taking of samples before cleaning and treatment with ÆGIS Microbe Shield and samples after you have treated.

As an example here we include the results of testing

Certificate of Analysis

Samples: Three samples of Aegis Antimicrobial Treated USB memory sticks received from XXXXXXXX 26th June 2007
Certificate No: 07F.149.BIO
Page: 1 of 1
Sample Ref: 7f / 095 - 096 & 149
Analysis Required: Activity against MRSA and Pseudomonas aeruginosa.
Samples Tested: 26th June 2007

Two of the USB memory sticks had been treated with a different concentration of ÆGIS antimicrobial agent on all sides Pseudomonas and MRSA organisms were grown on an agar plate and harvested into sterile hard water.

One stick of each treatment plus an untreated control was used for each organism.

The bacteria were applied in low numbers by contaminating a piece of petri - film with a low level dose of the organisms and wrapping the petri-film around the card allowing contact for one minute before removing the film.

The sticks were allowed to air dry at room temperature for one hour and three hours and swabs taken from one side of each card and each organism at these times. The number of surviving organisms for each time interval was determined using standard microbial recovery and counting techniques. Results obtained are tabulated below.

The first test was based on the application of ÆGIS at 1.5%. The USB sticks were tested after 1 hour and 3 hours.

  Pseudomonas MRSA
After 1 hour    
Count 40 38
Percentage kill 92.59% 90.45%
After 3 hours    
Count 12 18
Percentage kill 97.88% 95.68%

The second test was based on the application of ÆGIS at 2%. The USB sticks were tested after 1 hour and 3 hours.

  Pseudomonas MRSA
After 1 hour    
Count 16 28
Percentage kill 97.04% 92.90%
After 3 hours    
Count 0 5
Percentage kill 100% * 98.80%

The final concurrent test was based on No Application of ÆGIS i.e. they were the control tests. The USB sticks were tested after 1 hour and 3 hours.

  Pseudomonas MRSA
After 1 hour    
Count 540 394
Percentage kill 0 0
After 3 hours    
Count 566 416
Percentage kill 0 0

This test shows how much more laboratory testing can do as opposed to ATP testing. It also shows how you might want to test different % of ÆGIS in treatments.

* - It also shows that having infected a USB stick with for example Pseudomonas that had been treated with ÆGIS that after 3 hours the chemical was still working and had a 100% kill rate. The control also shows that on the untreated USB stick both the Pseudomonas and MRSA had continued to replicate.

Independent laboratories

There are thousands of independent laboratories around the world that can undertake this sort of testing for you. The benefit of choosing an independent laboratory is that you are seen as not having marked your own work!