Legionella

 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 a certified laboratory (CDC ELITE, NELAP, EPA and various states) and has analyzed more than 3,500 samples for Legionella.

Dr. Colin Fricker, ASI Technical Director, has contributed to the World Health Organization (WHO) Water Quality Guidelines, is a member and group convener of the ISO Group for Water Microbiology and a member of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). 

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 play as large or small a role as needed, from performing risk assessment and serving on your HACCP team, to simply receiving and analyzing samples.

ASI is accredited under NELAP through the FL-DOH for various samples matrices and analyses, is a USEPA Approved Laboratory under the LT2 Laboratory Quality Assurance Program, and holds certification from various states.

ASI is also a participant and "Member in Good Standing" of the US Centers for Disease Control and Prevention (CDC) "ELITE" Program, which is a voluntary proficiency testing program for Legionella

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's procedure is based on the CDC procedure, which uses Buffered Charcoal Yeast Extract media with additives.  After initial incubation (7 days), 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 is typically performed using latex agglutination or fluorescence antibody testing, and 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 188P?

The American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE) has developed proposed Standard 188P "Prevention of Legionellosis Associated with Building Water Systems" that prescribes specific risk management practices to prevent legionellosis.  ASHRAE 188P has been released twice for public comment and is expected to be adopted in 2013. 

Essentially, Standard 188 will require 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 HACCP risk management team must be established and a written HACCP plan developed. 

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 will ASHRAE 188 apply to?

Standard 188 will apply to human occupied buildings, except single-family residences (see Standard 188P Sections 2 and 5 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?

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 188P and HACCP?

Testing is a requirement - HACCP requires that critical limits be established at each critical control point and that testing be performed according to a set schedule to verify that the limits are being met. 

However, testing for Legionella specifically is not necessarily required - Standard 188P also requires that the HACCP team determine whether or not to test for Legionella specifically and if so, at what points and frequencies. 

Regarding testing for Legionella, Standard 188P Appendix B, Section 3 states:

  • "…biocide use in cooling tower utility water systems is important for Legionella control.  However, there are no biocides or combinations of that eliminate Legionella under all conditions, and high levels of Legionella colonization have been documented with all biocide combinations." 
  • "…the HACCP team should consider the value of determining if Legionella are present at detectable quantities in the water system."
  • "Culture remains the recommended method of Legionella testing" (ASI's method is based on the CDC culture method)
  • "Laboratory results should include the specific reporting of Legionella pneumophila serogroup 1" (ASI detects and reports L. pneumophila serogroup 1)
  • "Laboratories chosen for the processing of water samples for Legionella should be accredited in environmental microbiology (e.g., EPA NELAP or AIHA EMLAP) and also specifically certified for Legionella in the CDC ELITE program."  (ASI meets these criteria.  ASI is NELAP accredited through the FL-DOH and is a Member is Good Standing in the CDC ELITE Program)

How is ASHRAE 188P 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