Legionella pneumophila

Janet E. Stout, PhD Special Pathogens Laboratory

Department of Civil and Environmental Engineering
University of Pittsburgh, Swanson School of Engineering
Pittsburgh, PA

Angella M. Goetz, RN, MNEd, CIC Senior Consultant

Special Pathogens Laboratory
Pittsburgh, PA

October 3, 2014


Legionella pneumophilais a common cause of both community-acquired and healthcare-associated pneumonia. Clinical manifestations are nonspecific, but high fever, diarrhea, and hyponatremia are often distinctive. Diagnostic modalities include culture on selective media and urinary antigen detection. Quinolone and macrolide antibiotics are highly effective when initiated early in the course. Endemic hospital-acquired Legionnaires' disease is often underdiagnosed and overlooked. Infection has been linked to drinking water distribution systems of acute care and extended care facilities, with warm water systems typically implicated. Health departments and public agencies have issued infection prevention guidelines aimed at preventing outbreaks in facilities in which Legionnaires' disease has been overlooked. These guidelines include diagnostic testing for Legionella infection and culturing of the drinking water distribution system. Superheating and flushing or hyperchlorination of the water distribution are short-term approaches to terminate an outbreak. Long-term systemic water treatment with copper-silver ionization, chlorine dioxide, and monochloramine has also been shown to be effective in controlling Legionella.Proactive culturing for Legionellaof the water distribution system when cases of hospital-associated Legionnaires' disease have not been discovered is an evidence-based method of prevention.