New Study Shows the Importance of Environmental Monitoring for Hospital-acquired Legionellosis

By Dr. Michael Berg, EMLab P&K Senior Molecular Biologist

Legionnaire's disease and pontiac fever are caused by Legionella bacteria, which are commonly found in community water and hospital water systems. We have previously discussed Legionella bacteria in a focus article of the Environmental Reporter issue in January 2007. A new study spearheaded by the University of Pittsburgh School of Medicine and published in the July 2007 issue of the journal Infection Control and Hospital Epidemiology, has now determined that environmental monitoring of hospital water systems can help predict the risk of hospital-acquired Legionella pneumonia. The study also questions the current policy of the Centers for Disease Control (CDC) not to recommend routine environmental monitoring.

This new study evaluated samples for water systems of 20 hospitals across the country from 2000 to 2002. Water samples from at least 10 separate locations at each facility were tested multiple times over the two-year period for a total of 676 environmental samples. The study also included Legionella tests of urine and/or sputum samples from 633 patients in 12 of the 20 hospitals. The researchers found that 14 (70%) of the hospital water systems tested positive for Legionella species, and that 6 (43%) of those had high-level colonization of the water systems (30% or more of the distal outlets tested positive). Hospital-acquired Legionella pneumonia was identified in 4 hospitals, all of which had a high-level colonization with L. pneumopohila serogroup 1. The authors of the article conclude from this new study that environmental surveillance for Legionella should be part of a proactive strategy for prevention of hospital-acquired legionnaire's disease.

References:
1. Stout J., et al. (2007). Role of environmental surveillance in determining the risk of hospital-acquired legionellosis: a national surveillance study with clinical correlations. Infection Control and Hospital Epidemiology 28 (7): 818-824.