Legionellales

{{Short description|Order of bacteria}}

{{Automatic taxobox

| image = Legionella_Plate_01.png

| image_caption = Legionella sp. under ultraviolet illumination

| taxon = Legionellales

| authority =

| subdivision_ranks = Families and genera

| subdivision = Legionellaceae

   Legionella

Coxiellaceae

   Aquicella

   Coxiella

   Diplorickettsia

   Rickettsiella

   "Ca. Berkiella"

   "Ca. Fiscibacter"

   "Ca. Ovatusbacter"

   "Ca. Pokemonas"Marcel Dominik Solbach, Michael Bonkowski and Kenneth Dumack (2021): [https://www.frontiersin.org/articles/10.3389/fcimb.2021.642216/full Novel Endosymbionts in Rhizarian Amoebae Imply Universal Infection of Unrelated Free-Living Amoebae by Legionellales]. In: Front. Cell. Infect. Microbiol., 8 March 2021, doi:10.3389/fcimb.2021.642216. Along with:
[https://www.eurekalert.org/pub_releases/2021-04/uoc-br043021.php 'Pokemonas': Bacteria related to lung parasites discovered, named after Pokémon]. On: EurekAlert! 30-Apr-2021.

}}

The Legionellales are an order of Pseudomonadota ("Proteobacteria"). Like all Pseudomonadota, they are Gram-negative.George M. Garrity: Bergey's Manual of Systematic Bacteriology. 2. Auflage. Springer, New York, 2005, Volume 2: The Proteobacteria, Part B: The Gammaproteobacteria They comprise two families, typified by Legionella and Coxiella, both of which include notable pathogens. For example, Q fever is caused by Coxiella burnetii and Legionella pneumophila causes Legionnaires' diseaseFraser, D.W., Tsai, T,. Orenstein, W., et al. (1977). Legionnaires' disease: description of an epidemic of pneumonia. New England Journal of Medicine. 297:1189–1197.McDade, JE., Shepard, C.C., Fraser, D.W., et al., (1977) Legionnaires' Disease — Isolation of a Bacterium and Demonstration of Its Role in Other Respiratory Disease. New England Journal of Medicine. 297: 1197–1203. and Pontiac fever.{{cite web|url=http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/PontiacFever/GeneralInformation/ |title=General Information- Pontiac Fever |publisher=HPA |access-date=2013-04-07}}[http://jid.oxfordjournals.org/content/191/9/1530.full.pdf]{{dead link|date=May 2021|bot=medic}}{{cbignore|bot=medic}}{{cite journal|title=Pontiac Fever Due to Legionella micdadei from a Whirlpool Spa: Possible Role of Bacterial Endotoxin |journal=The Journal of Infectious Diseases |volume=184 |issue=10 |pages=1289–1292 |publisher=Jid.oxfordjournals.org |doi=10.1086/324211 |pmid=11679917 |year=2001 |last1=Fields |first1=Barry S. |last2=Haupt |first2=Thomas |last3=Davis |first3=Jeffrey P. |last4=Arduino |first4=Matthew J. |last5=Miller |first5=Phyllis H. |last6=Butler |first6=Jay C. |doi-access=free}}

Members of the order Legionellales can be molecularly distinguished from other Gammaproteobacteria by the presence of four conserved signature indels (CSIs) in the proteins tRNA-guanine(34) transglycosylase, lipoprotein-releasing system transmembrane protein lolE and tRNA (guanosine(37)-N1)-methyltransferase TrmD.{{Cite journal|last1=Saini|first1=Navneet|last2=Gupta|first2=Radhey S.|date=July 2021|title=A robust phylogenetic framework for members of the order Legionellales and its main genera (Legionella, Aquicella, Coxiella and Rickettsiella) based on phylogenomic analyses and identification of molecular markers demarcating different clades|url=https://link.springer.com/10.1007/s10482-021-01569-9|journal=Antonie van Leeuwenhoek|language=en|volume=114|issue=7|pages=957–982|doi=10.1007/s10482-021-01569-9|pmid=33881638|s2cid=233326323|issn=0003-6072}}