As a result of the Legionnaires’ Disease outbreak that occurred in the Bronx in August, 2015 both the State of New York and New York City Department of Health and Mental Hygiene have passed the first US regulations specifically for testing cooling towers (and drinking water systems in healthcare facilities) for Legionella. The regulations specify action levels for requiring cooling tower disinfection. In addition the US Centers for Disease Control and Prevention (CDC) recommends routine monitoring for Legionella in all hospitals in the US that perform bone marrow and organ transplants. Routine monitoring in hospitals is required or recommended in NY, TX, MD, Los Angeles County and Allegheny County PA. Canada has guidelines for monitoring healthcare facilities and certain provinces in Canada have regulations for monitoring government owned or leased buildings. On June 26, 2015 The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) passed ASHRAE Standard 188 for the prevention of legionellosis in buildings. While this voluntary standard of practice doesn’t specifically address Legionella testing, it does offer basic recommendations for establishing a building water safety plan
SAMPLING and ANALYSIS
Take a 1000 ml sample for potable water or a 250 ml sample for non-potable water. Be sure to use sterile bottles containing a chlorine neutralizing agent. Since biofilms are the actual reservoirs for the bacteria, it is also recommended to take sterile swab samples of biofilm in areas where it is present. Samples should be shipped overnight to the lab on freezer packs.
Analyzing for Legionella in environmental samples is difficult and time consuming. Therefore analysis should be conducted by a certified and trained professional. These culture tests have a turnaround time of 10 business days and provide confirmed identification and enumeration of the organism. Unfortunately the culture test cannot be rushed. Testing by Polymerase Chain Reaction (PCR) takes 2 to 3 days and may be useful for providing fast, presumptive results when a case or outbreak is encountered. Testing by Next Generation Whole Genome Sequencing (WGS) will provide a genetic fingerprint that will identify a link between an environmental source isolate to a patient clinical isolate and test relatedness as well. The use of Pulsed Field Gel Electrophoresis (PFGE) or Sequence Based Typing (for L. pneumophila serotype 1) has been replaced by Whole genome Sequencing. WGS has the discriminatory power to determine unequivocally if the molecular fingerprints from pure culture isolates are related based comparing the similarity/difference between the 3.4 Million individual genomic units of the bacterium.