''Actinomyces israelii'' is a species of

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

, rod-shaped

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 ...

within the genus ''

Actinomyces ''Actinomyces'' is a genus of the Actinomycetia class of bacteria. They all are gram-positive. ''Actinomyces'' species are facultatively anaerobic and they grow best under anaerobic conditions. ''Actinomyces'' species may form endospores, an ...

''. Known to live commensally on and within humans, ''A. israelii'' is an opportunistic pathogen and a cause of

actinomycosis Actinomycosis is a rare infectious bacterial disease caused by ''Actinomyces'' species. The name refers to ray-like appearance of the organisms in the granules. About 70% of infections are due to either ''Actinomyces israelii'' or '' A. gerencseria ...

. Many physiologically diverse strains of the species are known to exist, though not all are strict anaerobes. It was named after the German surgeon

James Adolf Israel James Adolf Israel (2 February 1848 – 2 February 1926) was a German surgeon. Academic background Israel was a native of Berlin, where he was born to Jewish parents. In 1870, Israel received his medical doctorate from Friedrich-Wilhelms ...

(1848–1926), who studied the organism for the first time in 1878.

Pathogenesis

Actinomycosis is most frequently caused by ''A. israelii''. It is a normal colonizer of the vagina, colon, and mouth. Infection is established first by a breach of the mucosal barrier during various procedures (dental, gastrointestinal), aspiration, or pathologies such as

diverticulitis Diverticulitis, specifically colonic diverticulitis, is a gastrointestinal disease characterized by inflammation of abnormal pouches—diverticula—which can develop in the wall of the large intestine. Symptoms typically include lower abdominal ...

. The chronic phase of this disease is also known as the "classic phase" because the acute, early phase is often missed by health care providers. This is characterized by slow, contiguous growth that ignores tissue planes and forms a sinus tract that can spontaneously heal and recur, leading to a densely fibrotic lesion. This lesion is often characterized as "wooden". Sulfur granules form in a central purulence surrounded by neutrophils. This conglomeration of organisms is virtually diagnostic of ''A. israelii.''

Treatment

''A. israelii'' is curable and can be treated with antibiotics. Both a sodium hypochlorite solution and calcium hydroxide can be highly effective in killing ''A. israelii'' when it has caused infection in the mouth.

References

External links

Type strain of ''Actinomyces israelii'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q147800 Actinomycetales Gram-positive bacteria Bacteria described in 1898