Legionella Testing & Consulting

Analytical Services, Inc. (ASI) has a long history of providing Legionella analyses to corporate facility/safety managers, healthcare facilities, laboratories, consultants, and other practitioners.  ASI is certified for Legionella testing by New York State (NYS-DOH-ELAP, Lab #12021, ISO 11731) and the CDC ELITE Program (since 2009), and has  analyzed more than 3,500 samples for Legionella.  

Frequently Asked Questions

What are Legionella?

Legionella are bacteria that live in aquatic environments.  Legionella are ubiquitous but typically present in naturals waters in very low concentrations.  However, in "built systems" (facility water systems, premise plumbing, etc.) under the right conditions, Legionella can colonize and amplify – and become potentially problematic if susceptible individuals are exposed to aerosolized water droplets. 

Specifically, Legionella are aerobic, non-spore forming, typically flagellated, Gram-negative bacteria.  The genus was named after a severe epidemic of pneumonia at an American Legion convention in 1976, which led to the isolation and characterization of L. pneumophila. Since then, over thirty (30) species of the genus Legionella have been identified.

 Where are Legionella found?

Legionella bacteria occur naturally in aquatic habitats and have been recovered from some municipal water supplies in the United States.  Low levels of Legionella in municipal water may seed industrial potable water systems and cooling water networks.  Legionella may then colonize and amplify in hot water tanks, humidifiers, water spray irrigation systems, cooling towers, ice machines, dead-legs in distribution systems, and other areas where bioflora are able to flourish.

Correlations between the presence of scale and sediment in distribution systems and the presence of Legionella have been noted in the literature.  Legionella have been shown to have some resistance to low levels of chlorine, and survives in municipal distribution systems because typical chlorine residuals may be insufficient to kill it.  Large distribution systems and building water systems may provide near optimal conditions for Legionella growth, including warm water temperatures and abundant nutrients contributed by sediments and biofilms.  In addition, the presence of amoebae and protozoa, which have been shown to harbor Legionella, may create a shielding effect, further reducing the effect of biocides.

 What is Legionellosis?  Is it different than Legionnaires Disease?

In humans, Legionella can cause two types of illness; Legionnaires' Disease (LD) and a less severe illness called Pontiac Fever.  Collectively, these are referred to as legionellosis. 

Legionnaires' Disease is difficult to diagnose as it produces symptoms very similar to a number of other respiratory infections.  Symptoms may include dry coughing, high fever, chills, diarrhea, shortness of breath, chest pains, headaches, excessive sweating, nausea, vomiting, and abdominal pain.  It can be fatal, particularly if the onset of treatment is delayed.  Pontiac fever is a nonfatal, nonpneumonic, influenza-like syndrome typified by headache, fever, and myalgia. 

The Centers for Disease Control (CDC) estimates that there are up to 18,000 cases of Legionnaires' disease occur annually in the United States – and that 10% of these cases are fatal. 

 Who needs to be concerned about Legionellosis?

Since Legionella bacteria are associated with water systems, anyone responsible for operation and maintenance of a water system should be concerned about Legionella and Legionellosis.  In addition, infection control specialists, managers of healthcare and eldercare facilities, corporate liability managers, etc. should be aware of the risks and best practices. 

Legionellosis cases result from the exposure of susceptible individuals to aerosolized water droplets that are contaminated with Legionella bacteria.  Typical routes of exposure include showers and other domestic water use, cooling towers, misters, humidifiers, etc., so any operations or risk manager associated with a facility with these risk factors should be especially vigilant.   

Typically, public water suppliers have less of a direct responsibility regarding legionellosis, since most instances of Legionella colonization and amplification occur in premise plumbing.  However, when outbreaks occur, public and media attention inevitably includes the public water supply, so preparation is advised.  (Also - see subsequent question on Public Water Supply)

 How can Analytical Services, Inc. (ASI) help me regarding Legionella?

ASI is a full service environmental microbiology laboratory that provides testing, research and consulting services to clients throughout the U.S. and internationally.  We can assist you in development of your water safety plan and will analyze samples.

For Legionella testing, ASI is certified under the CDC ELITE Program (since 2009) and by the State of New York (NYS-DOH-ELAP Lab #12021, ISO 11731 method).  As a certified, thrid party laboratory , we can test compliance and non-compliance samples without any conflict of interest (we do not sell water treatment chemicals or provide related services).

What is the procedure for Legionella testing?

The "gold standard" for Legionella testing is a traditional culture method, which uses selective agar for the recovery and enumeration of Legionella.  ASI has analyzed more than 3,500 samples for the presence of Legionella, from clients throughout the U.S.

 ASI performs a CDC-based procedure and also ISO 11731, both of which are culture based protocols that use Buffered Charcoal Yeast Extract media with additives.  After initial incubation, colonies with morphologies similar to Legionella are patch-plated to distinguish non-Legionella isolates.  At the end of this (typically 48 hour) incubation, isolates meeting Legionella criteria are referred to as "Presumptive Positives."  ASI provides Legionella confirmation, if requested, by serogrouping representative isolates for each presumptive positive sample.  Serogrouping can be performed serveral ways, including latex agglutination, fluorescence antibody testing, biochemical); ASI uses PCR (polymerase Chain Reaction).  ASI's serogrouping allows differentiation of  L. pneumophila Serogroup 1 (which accounts for more than 90% of LD cases), other serogroups of L. pneumophila and other species of Legionella  ASI also performs DNA extraction and genetic sequencing if needed.

 What is ASHRAE 188-2015?

The American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE) has developed roposed Standard 188 "Prevention of Legionellosis Associated with Building Water Systems" that prescribes specific risk management practices to prevent legionellosis.  

Essentially, Standard 188-2015 requires the following:

  • Each building must be reviewed to assess risk based on specific criteria
  • If one or more of the risk factors are present, a written water safety plan should be created and implemented.   

ASHRAE is also currently updating Guideline 12-2000 "Minimizing the Risk of Legionellosis Associated with Building Water Systems" that will include specific recommendations regarding the implementation of the risk management practices in Standard 188. 

Who/What does ASHRAE 188 apply to?

Standard 188 applies to human occupied buildings, except single-family residences (see Standard 188 Section 2 for more details).  It will apply to existing buildings and new construction alike. 

Many observers expect Standard 188 will be adopted into local and state building codes and would therefore be the legal standard or at least will establish the industry best practices.  Either way, Standard 188 is expected to have significant legal ramifications with respect to allegations of negligence in facility management.

 What is HACCP?

(Note: ASHRAE 188-2015 no longer includes the term "HACCP"  but it was in the first few drafts and the general approach followed in 188 is similar.)  

HACCP stands for "Hazard Analysis and Critical Control Point" and is a systematic method of assessing and controlling risk.  The HACCP approach was developed in the 1960s under work for NASA and has been applied extensively in the food industry as well as in pharmaceuticals, cosmetics, etc. 

Essentially a HACCP plan addresses (a) what are the hazards, (b) how are they being controlled and (c) how do you know the controls are working?

There are seven essential steps in HACCP:

  • Conduct a hazard analysis
  • Identify critical control points
  • Establish critical limits for each critical control
  • Establish monitoring for the control at each critical control point
  • Establish corrective actions
  • Establish verification and validation procedures for the HACCP plan
  • Establish documentation procedures

How is ASHRAE 188P different from TJC Standards (healthcare)?

The Joint Commission (TJC), formerly the Joint Commission on Accreditation of Healthcare Organizations or JCAHO, require management of healthcare facility systems to prevent waterborne disease – but do not proscribe specific steps regarding how this should be accomplished.  In contrast, ASHRAE 188 specifies the risk management approach.

How does testing fit into ASHRAE 188-2015?

Monitoring of controls measures established in the water safety has to be performed at designated intervals to ensure they are within the specified limits.  In addition, "Confirmation" includes "Validation" - which is defined in ASHRAE 188-2015 as: "initial and ongoing confirmation that the Program, when implemented as designed, effectively controls the hazardous conditions throughout the building water systems."  

Legionella growth is the hazardous condition you are trying to control - and monitoring for Legionella provides the most direct empirical evidence of program efficacy.  However, ASHRAE 188-2015 does not require Legionella analysis, this decision is left to the Program Team (see Section 7.3.5.d)

Informative Annex C in ASHRAE 188-2015 is titled "Guidance if Legionella Testing is Utilized" and states that the laboratory used should have demonstrated proficiency in Legionella detection, should be accredited by an accrediting body to a nationally or internationally recognized standard, with Legionella culture testing included in the laboratory's scope of accreditation.  ASI MEETS ALL OF THESE REQUIREMENTS; ASI is CDC ELITE certified since 2009, is NYS-DOH-ELAP certified for Legionella by ISO 11731 (Lab #12021).

How is ASHRAE 188 different from VHA Directive 2008-010?

The Veterans Health Administration (VHA) Directive 2008-010 applies only to VHA facilities.  It is VHA policy that all inpatient facilities implement an annual evaluation for Legionnaires' Disease prevention in accordance with a facility management plan.  Directive 2008-010 established guidelines for annual evaluation of Legionella risk at VHA inpatient facilities and presents guidelines for evaluations by facility type, including:

  • VHA Acute Care (non-transplant) facility
  • Nursing Home Care Unit (NHCU)
  • VHA-designated Transplant Center or Immediate Post-transplant care center

As a Public Water Supplier, do I need to be concerned about Legionella?

Water Quality Managers at PWSs should be aware of, and prepared for, Legionella concerns in the public.  Inevitably, when a case of Legionnaires' Disease is reported, someone raises questions regarding the water supply. 

While Legionella have been found in potable water distribution systems, the concentration at which they are found is usually insufficient to be of public health concern.  In cold water (<20°C) Legionella may be out-competed by other organisms, while in warmer waters (20 – 50°C) Legionella can proliferate. Regular monitoring of municipal supplies can determine the concentration of organisms present.  This information can be used to assess if any additional flushing or disinfection should be undertaken and can also be extremely useful if a Legionella outbreak should occur in the general area.  Demonstrably low Legionella counts within the municipal system indicates that infection is extremely unlikely to have occurred as a result of Legionella growing in the municipal system.  

For more information, please click Here for ASI’s technical document regarding Legionella or contact our Clients Services team