Legionella nagasakiensis

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A Microbial Biorealm page on the genus Legionella nagasakiensis

Classification

Higher order taxa

Domain (Bacteria); Phylum (Proteobacteria); Class (Gammaproteobacteria); Order (Legionellales); Family (Legionellaceae); Genus (Legionella)

Species

Species (nagasakiensis)

Legionella nagasakiensis

Description and significance

L. nagasakiensis is very similar to other species of Legionella, but differs due to a variety of novel proteins and other molecules not seen in the other 52 species. It is a gram negative bacillus although depending on conditions it can appear to be slightly coccoid as well. Also, like the other species of Legionella, it causes Legionnaires disease. There are several strains of nagasakiensis found through the world, two strains were found in Australian drinking water, one in a U.S Legionnaires patient, and the initial strain was found at the Nagasaki Municipal Medical Center, Japan thus its name [1].

Genome structure

L. nagasakiensis produces a unique autoinducer called Legionella autoinducer-1 which is responsible for the organisms quorum sensing. Quorum sensing is the ability to determine the surrounding population density of members of the same species and adjust the individual’s physiology to match the conditions. Nagasakiensis’ genome shares only a 29% genomic similarity to its closest sister species- Legionella oakridgensis making it a novel species. Other strains of Legionella only shared roughly a 10% similarity [1]. However nagasakiensis is not so dissimilar that it belongs to another genus, its 16S rDNA gene sequence shares an 96.6% relatedness to its sister species [2].

Cell and colony structure

The cell is motile due to a single flagella at the rear of the cell and is able to propel itself along. Due to the flagella the colonies tend to be more dispersed than other non-motile bacteria that clump together as a result. They have two stages, a non-motile stage where they reproduce, and a motile stage where they are highly infectious.

Metabolism

Rahnella aquatilis is a facultative anaerobe (it can live in the absence or presence of oxygen) that fixes Nitrogen [2]. R. aquatilis metabolizing whey lactose produces high levels of organic acids (except for lactic acid) [7].

Ecology

Rahnella aquatilis is named so because of its prevalence in fresh water. It has been found around the globe in places like the United States, Korea, Japan, Russia, the Ukraine, and Egypt. R. aquatilis has also been found in humans, soil, and snails [5]. One of the most unusual places for the the microbe to have been found was inside the gut of certain speicies of longicorn beetles in Korea [4].

Pathology

Rahnella aquatilis is pathogenic in humans. The organism can be diagnosed in patients via blood cultures, respiratory washings, and in wound cultures. Various infections, such as bacteremia (from renal infection), sepsis, respiratory infection, and urinary tract infection can be the result. One case involved an 11-month-old girl with congenital heart disease who developed infective endocarditis [8]. Another case involved a 76-year-old male who had prostatic hyperplasia presenting with acute pyelonephritis [9]. It is noted that R. aquatilis can potentially cause life-threatening infections in humans, infants and adults alike, especially the immunocompromised and organ transplant recipients. Treatments have included intravenous and oral levofloxacin therapy (and other members of the quinolone family).

References

[1] Yang Genyan, Robert F. Benson, Rodney M. Ratcliff, Ellen W. Brown, Arnold G. Steigerwalt, W. Lanier Thacker, Maryam I. Daneshvar, Roger E. Morey, Atsushi Saito and Barry S. Fields (2012). Legionella nagasakiensis sp. nov., isolated from water samples and from a patient with pneumonia. International Journal of Systematic and Evolutionary Microbiology 62, 284–288. DOI 10.1099/ijs.0.027193-0

[1] Furuhata Katsunori, Akiko Edagawa, Hiroshi Miyamoto, Keiichi Goto, Shin-Ichi Yoshida, Masafumi Fukuyama (2011). The first case of Legionella nagasakiensis isolation from hot spring water. https://www.jstage.jst.go.jp/article/bio/16/4/16_4_171/_pdf Biocontrol Science Vol. 16, Issue 4, 171-176.

[1] Meghan M. Pearce, Nicole Theodoropoulos, Gary A. Noskin, John P. Flaherty, Mary E. Stemper, Teresa Aspeslet, Nicholas P. Cianciotto, and Kurt D. Reed (2011). Native valve endocarditis due to a novel strain of Legionella. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3165573/ Journal of Clinical Microbiology 49(9): 3340–3342. PMCID: PMC3165573

[1] GenBank: ACI87823.1 macrophage infectivity potentiator protein, partial [Legionella nagasakiensis] http://www.ncbi.nlm.nih.gov/protein/ACI87823.1