Ecology of Legionella: From data to knowledge with a little wisdom

Abstract

The respiratory diseases produced by the Legionella genus of bacteria are collectively called Legionellosis. Presently more than 34 species of Legionella have been identified, 20 of which have been isolated from both environmental and clinical sources. The diseases produced by Legionella include the pneumonic form, Legionnaires' disease, and the flu-like form, Pontiac fever. Because the vast majority of Legionellosis is caused by the L.pneumophila species, this bacterium is the thrust of the discussion.Legionella is a global bacterium. The relationship of the bacterium to its environment has told us many things about infectious diseases. Not until Legionellosis and the discovery of its etiologic agent, Legionella, has such a successful modern-day marriage been consummated between the agent and its environment. Nearly two decades have passed since the term Legionellosis found its way into the vocabulary of the scientific journals, the popular press, and courtroom proceedings. Too often the scientific development, engineering implementation, and societal acceptance are disconnected. The focus of scientific research sometimes does not reflect engineering or societal needs and thus contributes little to the solution of immediate and important problems. At other times, scientific knowledge that could contribute to solutions is overlooked because of poor communication between the problem holders, the scientific community, regulatory agencies, the problem makers, and the public.The scope of this paper provides insights on the ecological niche of Legionella, describes the organism's ecological relationships in the natural world, and provides wisdom for effective control of the bacterium for the industrial and user communities.

Low Intraspecific Diversity in a Polynucleobacter Subcluster Population Numerically Dominating Bacterioplankton of a Freshwater Pond

“…The numerically significant contribution of free-living stages of facultative endosymbionts or facultative parasites of protists (e.g., Legionella spp.) to total numbers of bacterial communities has not been observed (17). However, detailed studies on PnecC bacteria have to reveal whether the endosymbiotic stages (26,44) and the observed free-living stages represent two completely independent lifestyles or only two stages of the same lifestyle (i.e., facultative endosymbionts).…”

Current and Emerging Legionella Diagnostics for Laboratory and Outbreak Investigations

“…are ubiquitous in freshwater habitats, including rivers, lakes, streams, ponds, hot springs, and subsurface waters, and are naturally part of microbial ecosystems ( Fig. 1) (30)(31)(32)(33). Several species have also been recovered from composts and potting mixes in the United States, Australia, and the United Kingdom and in the soil of Thai farmland (34)(35)(36)(37)(38)(39)(40)(41).…”

Amoebae as Training Grounds for Intracellular Bacterial Pathogens

“…Interaction between L. pneumophila and protozoa is considered to be central to the pathogenesis and ecology of L. pneumophila (46,85). In humans, L. pneumophila reaches the lungs after inhalation of contaminated aerosol droplets (33,36). The main sources of contaminated water droplets are hot water and air-conditioning systems, but the bacteria have been isolated from fountains, spas, pools, dental and hospital units, and other man-made water systems (36).…”