''Alcaligenes'' is a genus of

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

, aerobic, rod-shaped bacteria in the order of

Burkholderiales The Burkholderiales are an order of ''Betaproteobacteria'' in the phylum ''Pseudomonadota''.George M. Garrity: '' Bergey's Manual of Systematic Bacteriology''. 2. Auflage. Springer, New York, 2005, Vol. 2: ''The Proteobacteria Part C: The Alpha-, ...

, family Alcaligenaceae.

History

The type species, ''A. faecalis'', was first isolated from stale beer by Johannes Petruschky in 1896. However, formal description was only finished in 1919 by Castellani and Chalmers. The name ''Alcaligenes'' has its origin in

Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...

and

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

and means "

alkali In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The a ...

-producing". Several species were previously placed in ''Alcaligenes'', but have since been moved to more appropriate genera. '' A. aestus'', ''A. aquamarinus'', '' A. cupidus'', '' A. pacificus'' and '' A. venustus'' were first reclassified to the genus '' Deleya'' and later merged into ''

Halomonas ''Halomonas'' is a genus of halophilic (salt-tolerating) bacteria. It grows over the range of 5 to 25% NaCl. The type species of this genus is '' Halomonas elongata''. Description Members of ''Halomonas'' are Gram-negative, rod-shaped bacteria, ...

'' in the class of

Gammaproteobacteria ''Gammaproteobacteria'' is a class of bacteria in the phylum ''Pseudomonadota'' (synonym ''Proteobacteria''). It contains about 250 genera, which makes it the most genus-rich taxon of the Prokaryotes. Several medically, ecologically, and scienti ...

. Other species were reassigned within the order of

. '' A. denitrificans'', '' A. piechaudii'', '' A. ruhlandii'' and '' A. xylosoxidans'' are currently placed in '' Achromobacter'', '' A. latus'' in '' Azohydromonas'', '' A. eutrophus'' in '' Wautersia'', and '' A. paradoxus'' in '' Variovorax''.

Morphology and biochemistry

Species of ''Alcaligenes'' are rods, coccal rods, or cocci, sized at about 0.5-1.0 x 0.5-2.6 μm. The slender rods are slightly curved, capsule forming, not spore-forming. They are usually motile with amphitrichous

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

and rarely nonmotile. They tend to be colorless. ''Alcaligenes'' species are obligately aerobic, but some can undergo anaerobic respiration if nitrate is present. They are non-fermenting. ''Alcaligenes'' species have been used for the industrial production of nonstandard amino acids.

Biology and pathogenesis

Species of ''Alcaligenes'' typically occur in soil and water or decaying materials and dairy products. '' A. faecalis'' is commonly found in the intestinal tracts of vertebrates, and is found as a harmless saprophyte in 5% – 19% of the human population. Infections from ''Alcaligenes'' species are uncommon and largely opportunistic. ''A. faecalis'' is a known causing agent of nosocomial bacterial sepsis in immunocompromised patients by contaminated hemodialysis or intravenous fluid. Cases of

meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, intense headache, vomiting and neck stiffness and occasion ...

peritonitis Peritonitis is inflammation of the localized or generalized peritoneum, the lining of the inner wall of the abdomen and covering of the abdominal organs. Symptoms may include severe pain, swelling of the abdomen, fever, or weight loss. One pa ...

enteric fever Enteric fever is a medical term encompassing two types of salmonellosis, which, specifically, are typhoid fever and paratyphoid fever. Enteric fever is a potentially life-threatening acute febrile systemic infection and is diagnosed by isolating ...

appendicitis Appendicitis is inflammation of the Appendix (anatomy), appendix. Symptoms commonly include right lower abdominal pain, nausea, vomiting, fever and anorexia (symptom), decreased appetite. However, approximately 40% of people do not have these t ...

cystitis A urinary tract infection (UTI) is an infection that affects a part of the urinary tract. Lower urinary tract infections may involve the bladder (cystitis) or urethra ( urethritis) while upper urinary tract infections affect the kidney (py ...

, chronic suppurative otitis media, abscesses,

arthritis Arthritis is a general medical term used to describe a disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, Joint effusion, swelling, and decreased range of motion of ...

pneumonitis Pneumonitis describes general inflammation of lung tissue. Possible causative agents include radiation therapy of the chest, exposure to medications used during chemo-therapy, the inhalation of debris (e.g., animal dander), aspiration, herbicide ...

and

endocarditis Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves. Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, o ...

associated with ''Alcaligenes'' have been reported, including a

zoonotic A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a virus, bacterium, parasite, fungi, or prion) that can jump from a non-human vertebrate to a human. When h ...

infection from

ferret The ferret (''Mustela furo'') is a small, domesticated species belonging to the family Mustelidae. The ferret is most likely a domesticated form of the wild European polecat (''Mustela putorius''), as evidenced by the ferret's ability to inter ...

s. An increased recovery rate of ''Alcaligenes'' species from patients with

cystic fibrosis Cystic fibrosis (CF) is a genetic disorder inherited in an autosomal recessive manner that impairs the normal clearance of Sputum, mucus from the lungs, which facilitates the colonization and infection of the lungs by bacteria, notably ''Staphy ...

was reported in 2001, though the most commonly identified strain ''A. cylosoxidans'' has since been transferred to '' Achromobacter''. ''A. faecalis'' infections can pose a challenge due to considerable resistance to commonly used antibiotics. The resistance is driven by the production of β-lactamases (such as OXA-10 and PER-1), efflux pumps like the AcrAB-TolC system, and mutations in the ''gyrA'' and ''parC'' genes, which decrease fluoroquinolone effectiveness. The bacterium also forms biofilms on medical devices, providing protection against both antibiotics and the host immune system. In recent years, extensively drug-resistant (XDR) strains have emerged, showing very limited susceptibility to most available antibiotics.

References

* *

External links

Alcaligenes
at Kenyon College. {{Authority control Burkholderiales Bacteria genera Pathogenic bacteria Taxa described in 1919