''Leptospira'' ( grc, leptos, italics=yes, 'fine, thin' and la, spira, links=no, 'coil') is a genus of
spirochaete
A spirochaete () or spirochete is a member of the phylum Spirochaetota (), (synonym Spirochaetes) which contains distinctive diderm (double-membrane) gram-negative bacteria, most of which have long, helically coiled (corkscrew-shaped or s ...
bacteria, including a small number of
pathogenic
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a ger ...
and
saprophytic
Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ( ...
species.
''Leptospira'' was first observed in 1907 in
kidney
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...
tissue slices of a
leptospirosis
Leptospirosis is a blood infection caused by the bacteria '' Leptospira''. Signs and symptoms can range from none to mild (headaches, muscle pains, and fevers) to severe ( bleeding in the lungs or meningitis). Weil's disease, the acute, sever ...
victim who was described as having died of "
yellow fever
Yellow fever is a viral disease of typically short duration. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains – particularly in the back – and headaches. Symptoms typically improve within five days. ...
".
Taxonomy
''Leptospira'', together with the genera ''Leptonema'' and ''Turneria'', is a member of the family
Leptospiraceae
The Leptospiraceae are a family of spirochete bacteria. It includes the genus ''Leptospira'' which contains some pathogenic species.
Systematic
These genera belong to the family Leptospiraceae:
* '' Leptonema'' (with species ''Leptonema illin ...
. The genus ''Leptospira'' is divided into 20 species based on DNA hybridization studies.
Pathogenic ''Leptospira''
:''Leptospira alstonii''
Smythe et al. 2013 Haake_et_al._1993.html" ;"title="''Leptospira alstoni''" Haake et al. 1993">''Leptospira alstoni''" Haake et al. 1993:''Leptospira interrogans''
(Stimson 1907) Wenyon 1926 emend. Faine and Stallman 1982 ["''Spirochaeta interrogans''"
Stimson 1907; "''Spirochaeta nodosa''"
Hubener & Reiter 1916; "''Spirochaeta icterohaemorrhagiae''"
Inada et al. 1916; "''Spirochaeta icterogenes''"
Uhlenhuth & Fromme 1916; "''Leptospira icteroides''"
Noguchi 1919]
:''Leptospira kirschneri''
Ramadass et al. 1992
:''Leptospira noguchii''
Yasuda et al. 1987
:''Leptospira alexanderi''
Brenner et al. 1999
:''Leptospira weilii''
Yasuda et al. 1987
:''Leptospira borgpetersenii''
Yasuda et al. 1987
:''Leptospira santarosai''
Yasuda et al. 1987
:''Leptospira kmetyi''
Slack et al. 2009
:''
Leptospira mayottensis''
Bourhy et al. 2014
Intermediates or opportunistic ''Leptospira''
:''Leptospira inadai''
Yasuda et al. 1987
:''Leptospira fainei''
Perolat et al. 1998
:''Leptospira broomii''
Levett et al. 2006
:''Leptospira licerasiae''
Matthias et al. 2009
:''Leptospira wolffii''
Slack et al. 2008
Non-pathogenic ''Leptospira''
:''Leptospira biflexa''
(Wolbach and Binger 1914) Noguchi 1918 emend. Faine and Stallman 1982 Wolbach_&_Binger_1914.html" ;"title="''Spirochaeta biflexa''" Wolbach & Binger 1914">''Spirochaeta biflexa''" Wolbach & Binger 1914:''Leptospira idonii''
Saito et al. 2013
:''Leptospira meyeri''
Yasuda et al. 1987
:''Leptospira wolbachii''
Yasuda et al. 1987
:''Leptospira vanthielii''
Smythe et al. 2013
:''Leptospira terpstrae''
Smythe et al. 2013
:''Leptospira yanagawae''
Smythe et al. 2013
Members of ''Leptospira'' are also grouped into
serovar
A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or cells are classified together based on their surface antigens, allowing the ep ...
s according to their antigenic relatedness. There are currently over 200 recognized serovars. A few serovars are found in more than one species of ''Leptospira''.
At its 2002 meeting, the Committee on the Taxonomy of Leptospira of the International Union of Microbiological Societies approved the following nomenclature for serovars of Leptospira. Genus and species names are italicized as usual, with the serovar name not italicized and with an upper case first letter.
:''Genus species'' serovar Serovar_name
For example:
*''Leptospira interrogans'' serovar Australis
*''Leptospira biflexa'' serovar Patoc
Phylogeny
The currently accepted taxonomy is based on the
List of Prokaryotic names with Standing in Nomenclature
List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the nomenclature, naming and Taxonomy (biology), taxonomy of prokaryotes, following the taxonomy requirements and rulings of the In ...
(LPSN) and
National Center for Biotechnology Information
The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. Th ...
(NCBI).
Morphology
Although over 200 serotypes of ''Leptospira'' have been described, all members of the genus have similar morphology. ''Leptospira'' are spiral-shaped bacteria that are 6-20 μm long and 0.1 μm in diameter with a wavelength of about 0.5 μm.
One or both ends of the spirochete are usually hooked. Because they are so thin, live ''Leptospira'' are best observed by
darkfield microscopy.
The bacteria have a number of degrees of freedom; when ready to proliferate via
binary fission
Binary may refer to:
Science and technology Mathematics
* Binary number, a representation of numbers using only two digits (0 and 1)
* Binary function, a function that takes two arguments
* Binary operation, a mathematical operation that ta ...
, the bacterium noticeably bends in the place of the future split.
Cellular structure
''Leptospira'' have a
Gram-negative
Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...
-like cell envelope consisting of a cytoplasmic and
outer membrane. However, the
peptidoglycan
Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most ba ...
layer is associated with the cytoplasmic rather than the outer membrane, an arrangement that is unique to
spirochetes. The two
flagella
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates.
A microorganism may have fro ...
of ''Leptospira'' extend from the cytoplasmic membrane at the ends of the bacterium into the
periplasmic space
The periplasm is a concentrated gel-like matrix in the space between the inner cytoplasmic membrane and the bacterial outer membrane called the ''periplasmic space'' in gram-negative bacteria. Using cryo-electron microscopy it has been found tha ...
and are necessary for the motility of ''Leptospira''.
The outer membrane contains a variety of
lipoproteins
A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, su ...
and transmembrane