The U.S. Center for Disease Control and Prevention has classified Legionnaires’ disease as “on the rise”. This makes the discovery of a new infective agent a matter of concern. Legionnaires’ disease is a specific, serious pneumonia caused by the inhalation of pathogenic bacteria (such as Legionella pneumophilia) from contaminated water droplets. People with compromised immune systems and the elderly are at the greatest level of risk.
While common in natural water systems, Legionella bacteria can enter purpose-built water systems (both hot and cold) through supply water. While numbers are often still low, what is concern is with poor water system design which can lead to conditions that can encourage proliferation of the bacteria.
Optimal conditions are where cold water is above 20oC and hot water is below 55oC. Poor design aids the possibility of proliferation, such as pipes that branch and which slowdown the flow of water, allowing bacteria to become attached.
One related risk factor is because Legionellales are associated with biofilms (the slime like material that encases bacterial populations), and they are more frequently found on submerged surfaces than in water columns.
The newly discovered Legionellales bacteria have been detected, living and multiplying as intracellular parasites in the cells of organisms, acting as hosts. Legionellales refers to the order of bacteria, which includes the Legionella group. The new organisms may be capable of the same disease transmission.
In particular, the hosts of these Legionellales are amoebae (the spherical shaped Thecofilosea). Researchers from the University of Cologne (Department of Zoology) have named one of the genera of bacteria they discovered ‘Pokemonas.’ The genus name ‘Pokemonas’ is a play on words based on the video game franchise ‘Pokémon’.
Three different organisms were isolated as part of the study and these have been named: “Ca. Fiscibacter pecunius”, “Ca. Pokemonas kadabra”, and “Ca. Pokemonas abra”.
One reason why the organisms of potential concern have not been discovered before is because the Thecofilosea amoebae have not been studies in any great detail.
The new finding suggests that host organisms for Legionella and related bacteria is probably far greater than previously thought. In particular, more amoebae may function as hosts for these organisms and hence act as disease vectors.
The new data may also help to ascertain how different Legionellales bacteria are related to each other and how they interact with their hosts, as well as providing more insight into infection pathways.
The research has been published in the journal Frontiers in Cellular and Infection Microbiology¸ in a paper headed “Novel Endosymbionts in Rhizarian Amoebae Imply Universal Infection of Unrelated Free-Living Amoebae by Legionellales.”
