Infection prevention personnel, facility engineers, clinicians and risk managers rely on advisory documents to provide direction on preventing Legionnaires' disease. However, existing guidelines from health organizations and professional organizations aren't in agreement on best practices for monitoring and disinfection. What's more some standards aren't evidence-based and others exclude environmental monitoring.  

See Legionella Guidelines Table for complete list of guidelines and standards from federal, state, health organizations and professional associations including ASHRAE, Cooling Technology Institute, and AWT. All are available to download as PDFs.

Legionella Guidelines that Recommend Culturing 
 

Allegheny County Legionella Guideline (1993)

The United States has lagged behind our European counterparts in producing engineering and water treatment standards designed to protect building occupants from the risk of Legionellosis in water systems. The earliest U.S. guidance document — Approaches to Prevention and Control of Legionella Infection in Allegheny County Health Care Facilities — was produced in 1993 by the Allegheny County Health Department (ACHD), Pittsburgh, Pennsylvania. Numerous hospitals were experiencing outbreaks of Legionnaires’ disease and the Centers for Disease Control & Prevention (CDC) approach of postponing environmental monitoring until after cases had occurred was deemed inadequate. 

A more proactive approach was needed and the ACHD guideline filled that void by recommending that healthcare facilities culture their water systems before cases of Legionnaires’ disease were diagnosed in their hospitals. Drs. Victor L. Yu and Janet E. Stout were instrumental in its development.

 Veterans Affairs Legionella Directive (2008)

One of the largest healthcare systems in the U.S. is the Veterans Healthcare System, comprising more than 150 healthcare facilities. In 2008, the VHA issued their own Legionella prevention guidance document – VHA DIRECTIVE 2008-010 Prevention of Legionnaires’ Disease. This directive is based on the ACHD guideline. The CDC guidelines were deemed to be “arguably out-of-date” and the VA determined that it should strive to exceed the CDC standards.  This guideline requires annual Legionella risk assessments that includes environmental cultures for Legionella.

The Centers for Disease Control & Prevention (2004)

Guidelines for the Prevention of Healthcare-associated Pneumonia describes the approach to prevention of healthcare acquired Legionnaires’ disease. This document states that environmental culturing of the hospital water system can performed as part of a comprehensive strategy to prevent Legionnaires’ disease in transplant patients.

For facilities with hemopoietic stem-cell- and/or solid-organ transplantation programs, periodic culturing for legionellae in water samples from the transplant unit(s) can be performed as part of a comprehensive strategy to prevent Legionnaires' disease in transplant recipients.

Australia-New Zealand

There are Legionella standards that are legally enforceable documents in the United Kingdom as well as Australia and many other countries. Many of these documents include culturing for Legionella as an integral part of the prevention plan. The Australian-New Zealand guideline is particularly useful in that it presents a very pragmatic approach to cooling tower maintenance.  Actions are recommended based on concentration-based targets from Legionella concentrations from periodic cultures.