How to Conduct a Legionella Report

legionella report are obligate intracellular gram-negative bacteria that can cause pneumonia in humans. The pathogen is able to thrive and grow in a biofilm that resists degradation, rendering the organism resistant to disinfectants. As a result, the ubiquity of legionella and some strains being pathogenic to humans necessitates continuous environmental monitoring in buildings for the presence of legionella and other pathogens.

The ASHRAE 188 standard and multiple guidance documents outline steps for management of Legionella in building water systems. These include the American Industrial Hygiene Association (AIHA, 2015), National Sanitation Foundation International standard 453, and guidance from Allegheny County, Pennsylvania, as well as New York City and State regulations for control of Legionella in cooling towers and in certain healthcare facilities.

Interpreting the Legionella Report: Understanding the Results

Laboratories can use several methods to analyze water system samples for the presence of Legionella. Culture techniques, which utilize specialized agar cultures such as buffered charcoal yeast extract (BCYE), can identify Legionella in the sample and report how many bacteria, or colony-forming units, are present per milliliter of sample. However, it may take up to 14 days to receive results.

Nucleic acid amplification methods offer greater sensitivity and speed for the detection of Legionella. These can also distinguish different serogroups of the bacteria, or even specific sequence types. However, further research is needed for better means of identifying the pathogenic strains involved in disease outbreaks, such as the more common L. pneumophila, which accounts for most legionellosis cases in the United States.