Why to adopt a microbiological
monitoring of your water circuits
by ATP-metry?

 

Most of the regulatory texts on the management of microbiological risks in water systems require operators to implement monitoring indicators to anticipate a drift of their installation that could lead to a positive culture result in regulatory control (Legionella or Pseudomonas, for example).

Choosing a monitoring indicator turns generally to a technology whose reliability, cost and ease of implementation make it possible to realize the test to a sufficiently high frequency to prevent this drift.

Among these microbiological indicators, the most popular on the market are the counting of revivable germs at 22°C or 36°C, the quantitative PCR, the qualitative ATP-metry (the "pen" format) and quantitative ATP-metry. The advantage and disadvantage of each of these measurement methods are summarized in the following table:

Monitoring indicator

Pros

Cons

Revivable germs at 22°C or 36°C on agar tab

- Easy and quick implementation (few seconds)
- Field test
- Cost (between 3 and 7€*)

- Response time (48h approx.)
- Monitored and calibrated heat chamber required
- Volume of water analyzed not very representative and not reproducible (1ml approx.)
- Counting of cultivable bacteria only (a large proportion of the germs of an ecosystem are in a non-cultivable state)

Quantitative PCR

- Specific counting of the desired germ 
- Quick and reliable results (between 4 and 48h)
- Quantification of the germ whatever the compartment (free, associated with a protozoan or a biofilm fragment ...) and physiological state in which it is (cultivable, non-culturable)

- Laboratory technique
- Cost of the analysis (between 70 and 150€*)

Qualitative ATP-metry ("pen" format tests)

- Quick and easy implementation (few seconds)
- Field test
- Cost (between 3 and 9€*)

- Qualitative test
- Irrelevant Unit (RLU)
- No discrimination of free ATP
- Volume of water analyzed unrepresentative and not repeatable (about 100µl)
- High threshold
- Inability to test the state of the enzyme and the possible inhibitory effect of the matrix analyzed

Quantitative ATP-metry

- Quick and easy implementation (few minutes)
- Quantification of the total flora (cultivatable viable microorganisms and non-cultivable viable microorganisms)
- Field test
- Quantitative Test (reporting results in picogram of ATP per milliliter and bacteria equivalents per milliliter
- Low threshold
- Use of an internal standard addition to ensure the accuracy of the result (validation of the enzymatic efficiency, taking into account the possible inhibitory effect of the matrix analyzed on the bioluminescence reaction, validation of the response of the luminometer and its linearity, repeatability and reproducibility of measurements)
- Cost (from 9 to 25 €*)

- Non-specific testing
- Conservation of reagents in the refrigerator or freezer

* Prices observed in 2014 in France.

 

The quantitative ATP-metry is proving to be one of the best indicators of biological monitoring on the market.

The implementation of a biomonitoring by quantitative ATP-metry allows you:

  1. To anticipate the drift of your system: improving health risk management, avoid production downtime related to regulatory overtaking (Legionella, Pseudomonas ...)
  2. To control the injection of biocidal products: use of a treatment strategy appropriate to the ecosystem, reducing the cost of the products (up to 40%), reducing the impact of biocidal products on the environment
  3. Evaluate the efficiency of your procedures: validation of the efficacy of the different phases (cleaning, disinfection, rinsing), implementation of adequate procedures, saving time (teams mobilization)
  4. To identify areas conducive to development: characterization of critical points and highlighting of malfunctions affecting microbiology, measurement of surfaces biofouling