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18th February 2021  Content supplied by: Diamidex

Water Testing: Get Faster Results with Pasteurian Culture 2.0


Water, a resource so common and indispensable to human life, can be contaminated in different ways by pathogenic bacteria. 

Coliforms, Escherichia coli, Pseudomonas aeruginosa, Legionella pneumophila... They all represent a danger to human health and can cause severe and even fatal infections.

According to the CDC, “About 7.2 million Americans get sick every year from diseases spread through water”. This is a public health issue that must be taken very seriously.

In this context, it appears crucial to test efficiently for the presence of these pathogenic bacteria. To date, traditional culture using the agar plate method remains the most reliable technique, delivering results in Colony Forming Units (CFUs). But this takes time, sometimes up to several days. 

Now, with the release of MICA microcolony counters by Diamidex, the Pasteurian microbial detection method can be a rapid method. 

Thanks to an unmatched optical resolution among colony counters combined with revolutionary tagging technology, the MICA Fluorescence and MICA Chromogenic allow the enumeration of culturable microorganisms in CFU, with a reduction in incubation time of between 40% and 80%. 

Advantages:

  • MICA Chromogenic solution for Coliforms/Escherichia coli provides a result in 10 hours compared to 24 hours with the standard method.

  • MICA Fluorescence solution for Legionella pneumophila provides a result in 48h instead of 10 days with the traditional culture method!

  • MICA Fluorescence solution for Pseudomonas aeruginosa provides a result in 14 hours (with no need of confirmation) instead of more than 24 hours with the standard procedure.

 

Coliforms and Escherichia coli

Environment & risks: These bacteria are naturally present in the digestive tract of warm-blooded animals. Therefore, their presence in water is a sign of human or animal faecal contamination. They can be found in outdoor bathing water but also in running water if the purification system fails. Drinking water must be void of coliforms to be considered safe.

Recommended culture method ISO 9308-1:2016: Filtration on the membrane → 24 hours incubation on chromogenic coliform agar medium → calculation of target microorganisms in CFU.

MICA Chromogenic optimizations for ISO 9308-1 culture method: Filtration on the membrane → 10 hours incubation on chromogenic coliform agar medium → automatic enumeration of the target microorganisms in CFU. No change needed or reagent added during the process, just earlier enumeration!

Pseudomonas aeruginosa

Environment & risks: They are found in soil, fresh water and even seawater. They can also proliferate on animals or plants and are frequently found in healthcare settings. They are responsible for thousands of deaths every year, especially because of water contaminations. Its growing resistance to antibiotic treatments makes it increasingly virulent and hard to treat.

Recommended culture method ISO 16266-2:2018: Filtration on the membrane → 24 hours culture on CN agar → confirmation via enzymatic test and calculation of the number of the target microorganisms in CFU.

MICA Fluorescence optimizations for ISO 16266-2:2018 culture method: Filtration on the membrane → 14 hours culture on CN agar → automatic enumeration of the target microorganisms in CFU. No change needed or reagent added during the process, just an earlier enumeration with no confirmation required!

Legionella pneumophila

Environment & risks: They are also naturally present in the environment, but it is in artificial networks that they best proliferate. Hot water networks especially provide all the right conditions for their rapid development: temperature between 25-45°C and the presence of biofilm on the pipe walls.

Infection is caused by breathing in aerosols during a simple shower or bath, for example. Legionella bacteria will then breed in the lungs until they cause acute pneumopathy: Legionnaire's disease. For the most frail, elderly or immunocompromised people, the mortality rate can rise from 10% to 50%. Since January 2021, it is now mandatory in Europe to test for the presence of Legionella in all drinking water networks.

Recommended culture method: ISO 11731: Filtration on the membrane → acid shock (+ thermic shock for cooling tower water) → 10 days incubation on GVPC agar plate → counting with the eye the number of target microorganisms in CFU → latex test for serotype confirmation.

MICA Fluorescence optimizations for ISO 11731 culture method: Filtration on the membrane → acid shock (+ thermic shock for cooling tower water) → 1 drop of Diamidex patented culture supplement → 48 hours incubation on GVPC agar plate → fluorescent tagging →  3 minutes automatic counting of the number of Legionella pneumophila all serotypes.

Other advantages:

  • one GVPC plate per sample

  • Reusable membrane for other serotyping tests

  • No uninterpretable results on dirty water (interfering flora does not have time to grow)

And soon, many other microorganisms will be available for both MICA Chromogenic and MICA Fluorescence!


    

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Date Published: 18th February 2021

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