Legionella is a bacterium that often goes unnoticed until it poses a serious health risk. They are often found lurking in water systems including hot tubs, plumbing systems, and cooling towers. There’s a growing concern about the risk associated with Legionella, as they lead to Legionnaires’ disease, a fatal form of pneumonia.
Because Legionella bacteria are mostly found in water, it’s easier for people to inhale aerosolized droplets of water containing Legionella, making them susceptible to contracting Legionnaires disease. Therefore, it’s important to prevent the infestation of Legionella in water systems. One way to prevent it is through regular Legionella testing and monitoring. This will help in the early detection and treatment of the disease in the water system.
Legionella testing and monitoring involves the sampling of water from different parts of a water system and testing it to detect the presence of the Legionella bacteria. If Legionella is discovered, steps can be taken to remove it from the water system, thereby preventing people from getting sick. You can visit https://www.hse.gov.uk/legionnaires/what-is.htm to learn more about Legionnaires’ disease.
In this article, we will explore how to test and monitor Legionella’s presence in the water system. We will also look at how to prevent and control Legionella growth.
Table of Contents
The Cultural Method
This is the traditional and most widely used method of detecting Legionella in water systems. However, it can take longer to get the results. In this method, you collect different water samples using clean and sterile bottles.
This involves the collection of water from stagnant, warm water such as showers, sinks, and faucets, or from warm-water systems evaporative condensers, cooling towers, and hot water storage tanks. The samples are sent to a reputable UKAS lab such as Total Water Compliance London for the testing of Legionella presence in the water. The process usually involves the following steps:
The provided water sample is first concentrated using a filtration technique, such as membrane filtration. This makes it easier to detect the Legionella bacteria in the water samples.
After concentration, the sample is inoculated on a selective agar medium, such as Glycine Vancomycin Polymyxin Cycloheximide (GVPC) agar or Buffered Charcoal Yeast Extract (BCYE) agar. Both media are enriched with nutrients and antibiotics that promote the growth of Legionella while suppressing other microorganisms. Click here to learn more about inoculation.
Next, the inoculated plates are incubated at an appropriate temperature, usually 35-37°C, for a specified period, usually 2-14 days.
After the incubation period, the plates are carefully examined for the presence of Legionella colonies. Legionella colonies usually exhibit characteristic features, such as their color and size, in their identification.
For confirmation, suspected Legionella colonies are tested further, such as biochemical assays or immunofluorescence antibody staining. This is to ascertain their presence or absence.
Assess the Number of Legionella Colonies
After confirming the presence of Legionella in the water, the next is to enumerate the number of Legionella colonies on the plate. Also, the concentration of Legionella in the water is analyzed.
Polymerase Chain Reaction (PCR) Method
This is another method of detecting Legionella in water. This is a rapid and sensitive molecular technique that specifically targets the DNA of Legionella bacteria.
It involves using a DNA extraction kit to extract the DNA of the Legionella bacteria from the water. Then the extracted DNA is subjected to PCR amplification, a process that replicates certain DNA sequences, with a target for the 16S rRNA gene of Legionella.
The amplified DNA is detected through different methods such as fluorescence detection and gel electrophoresis. Lastly, the amount of amplified DNA is quantified. This results in an indication of the Legionella concentration in the water used.
How to Prevent Legionella Bacteria From Water Infestation
Preventing Legionella bacteria from water infestation involves implementing a combination of diverse measures, including temperature control, regular cleaning, and disinfection.
By Maintaining Water Temperature
Legionella bacteria thrive best in warm water, between 25°C and 45°C. By keeping water temperatures above 50°C or below 20°C, it can hinder the growth of the bacteria.
Cleaning and Disinfection
This can be done using chemical disinfectants, such as chlorine or bromine, or simply by heat. Disinfecting will help lessen the possibility of the water system getting infestation by Legionella.
Removing Dead Legs
There are sections in your water system that you are no longer using. It’s a perfect spot for the growth of Legionella, so it’s important to eliminate them by rerouting pipes or removing the pipes completely.
By Installing Filters
Filters can go a long way in removing Legionella bacteria from water. This is especially important for people who are at risk of Legionella disease, such as people with weakened immune systems.
Legionella is a bacterium that survives majorly in water systems and causes great damage to human health. They are mostly found in stagnant, warm waters of water systems. It can cause a form of pneumonia called Legionnaires disease when people inhale droplets of water containing Legionella.
Legionella testing and monitoring are important for the detection and treatment of Legionella and prevent people from getting ill. Remember, the removal of dead logs, maintaining water temperature, and cleaning and disinfection are essential in preventing Legionnaires disease and ensuring the safety of water systems.