Proteus Bacteria
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''Proteus'' is a genus of
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 wall ...
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
. ''Proteus'' bacilli are widely distributed in nature as saprophytes, being found in decomposing animal matter, sewage, manure soil, the mammalian intestine, and human and animal feces. They are opportunistic pathogens, commonly responsible for urinary and septic infections, often
nosocomial A hospital-acquired infection, also known as a nosocomial infection (from the Greek , meaning "hospital"), is an infection that is acquired in a hospital or other health care facility. To emphasize both hospital and nonhospital settings, it is ...
. The term
Proteus In Greek mythology, Proteus (; Ancient Greek: Πρωτεύς, ''Prōteus'') is an early prophetic sea-god or god of rivers and oceanic bodies of water, one of several deities whom Homer calls the "Old Man of the Sea" ''(hálios gérôn)''. ...
signifies changeability of form, as personified in the Homeric poems in Proteus, "the old man of the sea", who tends the sealflocks of Poseidon and has the gift of endless transformation. The first use of the term “Proteus” in bacteriological nomenclature was made by Hauser (1885), who described under this term three types of organisms which he isolated from putrefied meat.


Clinical significance

Three species—'' P. vulgaris'', '' P. mirabilis'', and '' P. penneri''—are
opportunistic Opportunism is the practice of taking advantage of circumstances – with little regard for principles or with what the consequences are for others. Opportunist actions are expedient actions guided primarily by self-interested motives. The term ...
human
pathogen 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 germ ...
s. ''Proteus'' includes pathogens responsible for many human
urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney ...
s. ''P. mirabilis'' causes wound and urinary tract infections. Most strains of ''P. mirabilis'' are sensitive to
ampicillin Ampicillin is an antibiotic used to prevent and treat a number of bacterial infections, such as respiratory tract infections, urinary tract infections, meningitis, salmonellosis, and endocarditis. It may also be used to prevent group B strepto ...
and
cephalosporin The cephalosporins (sg. ) are a class of β-lactam antibiotics originally derived from the fungus ''Acremonium'', which was previously known as ''Cephalosporium''. Together with cephamycins, they constitute a subgroup of β-lactam antibiotics ...
s. ''P. vulgaris'' is not sensitive to these antibiotics but
ticarcillin Ticarcillin is a carboxypenicillin. It can be sold and used in combination with clavulanate as ticarcillin/clavulanic acid. Because it is a penicillin, it also falls within the larger class of beta-lactam antibiotics. Its main clinical use is as ...
. However, this organism is isolated less often in the laboratory and usually only targets immunosuppressed individuals. ''P. vulgaris'' occurs naturally in the intestines of humans and a wide variety of animals, and in manure, soil, and polluted waters. ''P. mirabilis'', once attached to the urinary tract, infects the kidney more commonly than ''E. coli''. ''P. mirabilis'' is often found as a free-living organism in soil and water. About 10–15% of
kidney stone Kidney stone disease, also known as nephrolithiasis or urolithiasis, is a crystallopathy where a solid piece of material (kidney stone) develops in the urinary tract. Kidney stones typically form in the kidney and leave the body in the urine s ...
s are struvite stones, caused by alkalinization of the urine by the action of the urease enzyme (which splits urea into ammonia and carbon dioxide) of ''Proteus'' (and other) bacterial species.


Identification

''Proteus'' species do not usually ferment
lactose Lactose is a disaccharide sugar synthesized by galactose and glucose subunits and has the molecular formula C12H22O11. Lactose makes up around 2–8% of milk (by mass). The name comes from ' (gen. '), the Latin word for milk, plus the suffix '' - ...
, but have shown to be capable glucose fermenters depending on the species in a triple sugar iron ( TSI) test. Since it belongs to the order
Enterobacterales Enterobacterales is an order of Gram-negative, non-spore forming, facultatively anaerobic, rod-shaped bacteria with the class Gammaproteobacteria. The type genus of this order is ''Enterobacter.'' The name Enterobacterales is derived from the ...
, general characters are applied on this genus. It is
oxidase In biochemistry, an oxidase is an enzyme that catalyzes oxidation-reduction reactions, especially one involving dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydro ...
-negative but
catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting t ...
- and
nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...
-positive. Specific tests include positive
urease Ureases (), functionally, belong to the superfamily of amidohydrolases and phosphotriesterases. Ureases are found in numerous bacteria, fungi, algae, plants, and some invertebrates, as well as in soils, as a soil enzyme. They are nickel-containin ...
(which is the fundamental test to differentiate ''Proteus'' from ''
Salmonella ''Salmonella'' is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' is the type species and is fur ...
'') and
phenylalanine deaminase The enzyme phenylalanine ammonia lyase (EC 4.3.1.24) catalyzes the conversion of L- phenylalanine to ammonia and ''trans''-cinnamic acid.: :L-phenylalanine = ''trans''-cinnamate + NH3 Phenylalanine ammonia lyase (PAL) is the first and committ ...
tests. On the species level,
indole Indole is an aromatic heterocyclic organic compound with the formula C8 H7 N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole is widely distributed in the natural environmen ...
is considered reliable, as it is positive for ''P. vulgaris'', but negative for ''P. mirabilis''. Most strains produce a powerful urease enzyme, which rapidly hydrolyzes urea to ammonia and carbon monoxide; exceptions are some Providencia strains. Species can be
motile Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...
, and have characteristic "
swarming Swarm behaviour, or swarming, is a collective behaviour exhibited by entities, particularly animals, of similar size which aggregate together, perhaps milling about the same spot or perhaps moving ''en masse'' or migrating in some direction. ...
" patterns. Underlying these behaviors are the somatic O and flagellar H antigens, so named based on Kauffman–White classification. This system is based on historic observations of
Edmund Weil Edmund Weil (16 April 1879 – 15 June 1922) was a German Bohemian bacteriologist. He is best known for the Weil–Felix test used in the diagnosis of Rickettsia, rickettsial infections. He conducted this research during World War I and died from a ...
(1879–1922) and Arthur Felix (1887–1956) of a thin surface film produced by agar-grown flagellated ''Proteus'' strains, a film that resembled the mist produced by breath on a glass. Flagellated (swarming, motile) variants were therefore designated H forms (German ''Hauch'', for film, literally breath or mist); nonflagellated (nonswarming, nonmotile) variants growing as isolated colonies and lacking the surface film were designated as O forms (German ''ohne Hauch'', without film .e., without surface film of mist droplets.Hahon, N., Ed. Selected Papers on the Pathogenic Rickettsiae, p. 79, Harvard University Press, 1968. The cell wall O-antigen of certain strains of'' Proteus'', such as OX-2, OX-19, OX-k, crossreact with several species of ''
Rickettsia ''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "rickett ...
''. These antigens can be used in laboratory to detect the presence of antibodies against certain ''Rickettsia'' species in patients' sera. This test is called Weil-Felix reaction after its originators.


See also

* Dienes phenomenon


References

{{DEFAULTSORT:Proteus (Bacterium) Bacteria genera