What Legionella Bacteria Levels Trigger a Response per CDC?

What Legionella Bacteria Levels Trigger a Response per CDC?
Part 3 of a 3-Part Series of interpreting the CDC’s latest Legionella bacteria sampling guidance  

By Hilary Nardone, Environmental Group Training Manager
Certified ASSE 12080 Legionella Water Safety and Management Specialist 


Image via CDC

Whenever positive Legionella bacteria results occur, it is useful to understand the appropriate action responses.  The CDC’s “Toolkit for Controlling Legionella in Common Sources of Exposure” (Legionella Control Toolkit) states that there is “no safe amount or type of Legionella,” emphasizing the importance of a response for any positive sample.  However, the concentration of each positive sample can determine what type of response is most beneficial.

What types of actions you may choose to implement:

Concentration of Legionella Bacteria (CFU/mL)  Suggested Response Actions 
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  • Review sample collection, handling, and testing for potential errors. 
  • Confirm that system equipment is in good working order and functioning as intended. 
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  • Review records to confirm that the WMP was implemented as designed (verification). 
  • Review assumptions about operating conditions, such as physical and chemical characteristics of incoming water. 
  • Re-evaluate fundamental aspects of the WMP, including analysis of hazardous conditions, cleaning, maintenance procedures, chemical treatment, and other aspects that could affect Legionella testing. 
  • Adjust WMP as necessary to address any deficiencies identified. 
  • Consider whether remedial treatment is needed only after completion of the above. 
  • If remedial treatment was performed, wait at least 48 hours after the system returns to normal operating conditions and retest a set of representative samples to confirm the effectiveness of the response. 

 

By partnering with Barclay for your Legionella bacteria sampling needs, you have automatic confirmation that the sample collection, handling, and testing for potential errors are regularly reviewed, as well knowing that the system equipment is in good working order and functioning as intended.  Barclay actively ensures that their third-party laboratory is held to the most rigorous standards, as well as being CDC ELITE accredited.

In instances where there are positive Legionella bacteria samples, Barclay will work with you to review your onsite operating conditions, as well as recommend updates to your WMP and both short- and long-term remediation strategies.  Since each facility has unique needs, these recommendations are tailored to address the specific needs to better minimize Legionella growth and amplification.

Don’t miss our previous two blog posts on this series:

 

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