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Biofilm Sampling


Instructions for Swab Sampling of Biofilm and Water Samples for Legionella Testing

(from Centers for Disease Control) Click Here


1.  Ask Facilities Management to remove aerators from shower heads and faucets where you will be sampling.


2. Turn on the water for a couple of seconds to moisten the pipe, and then turn it off. Insert the EMSL swab deep into the faucet/pipe. Try to get beyond the bend and swab around the inside surface firmly without breaking the swab stem. (If there is visible biofilm on the inside of the showerhead or faucet aerator when these are removed, they can also be swabbed.)


3. Place the swab into the EMSL sterile plastic tube and add 3–5 mL of water from the same faucet to keep the swab tip moist during transport. Snap the wooden or plastic swab stem approximately 1 in. from the top of the tube. Add a drop of 0.1N sodium thiosulfate solution provided to neutralize residual disinfectants. Tighten the tube top to prevent leakage.


4. Label the tube with a unique identifier. Record the type and location of the sample on a Sample Data Sheet, and place the tube into a cooler. Take bulk water samples:


5. After the biofilm swab is collected, turn on the water and let it run for a few minutes until the water is warm but not hot. The goal is to obtain water currently in the distribution system along with any material shed from biofilm. Avoid heating water excessively (approximately 122°F or higher) since free-floating Legionella will die quickly at elevated temperatures. Collect 1 L of water from the faucet into a sterile 1 L bottle, leaving a 1 in. space at the top. Tighten the top to prevent leakage.


6. Label the bottle with a unique identifier. Record the type and location of the sample on the Sample Data Sheet, and place it into the cooler.  Samples should be sent to the lab by overnight shipping.


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Latest Article

An Overview of Legionella Analyses

By Diane Miskowski, MPH EMSL Analytical, Inc.

The first recognized outbreak of Legionnnaires' Disease occurred in the US at the American Legion Convention in Philadelphia during the summer of 1976. read more...

Additional Resources

For additional information please click the links below.

Legionnaires' Disease
Clinical Microbiology Reviews
Cooling Technology Institute
more resources...

Legionella images courtesy of CDC, Public Health Image Library (PHIL)


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