Actinomyces

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Actinomyces
Actinomyces israelii.jpg
Scanning electron micrograph of Actinomyces israelii
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Domain: Bacteria
Phylum: Actinomycetota
Class: Actinomycetia
Order: Actinomycetales
Family: Actinomycetaceae
Genus: Actinomyces
Harz 1877 (Approved Lists 1980) [1]
Species

See text.

Synonyms
  • "Actinobacterium" Sampietro 1908
  • "Odontomyces" Howell et al. 1965

Actinomyces is a genus of the Actinomycetia class of bacteria. They all are gram-positive and facultatively anaerobic, growing best under anaerobic conditions. [2] Actinomyces species may form endospores, and while individual bacteria are rod-shaped, Actinomyces colonies form fungus-like branched networks of hyphae. [3] The aspect of these colonies initially led to the incorrect assumption that the organism was a fungus and to the name Actinomyces, "ray fungus" (from Greek actis, ray or beam, and mykes, fungus).

Contents

Actinomyces species are ubiquitous, occurring in soil and in the microbiota of animals, including the human microbiota. They are known for the important role they play in soil ecology; they produce a number of enzymes that help degrade organic plant material, lignin, and chitin. Thus, their presence is important in the formation of compost. Certain species are commensal in the skin flora, oral flora, gut flora, and vaginal flora [4] of humans and livestock. They are also known for causing diseases in humans and livestock, usually when they opportunistically gain access to the body's interior through wounds. As with other opportunistic infections, people with immunodeficiency are at higher risk. In all of the preceding traits and in their branching filament formation, they bear similarities to Nocardia . [5]

Like various other anaerobes, Actinomyces species are fastidious, thus not easy to culture and isolate. Clinical laboratories do culture and isolate them, but a negative result does not rule out infection, because it may be due simply to reluctance to grow in vitro .

Genomics

Phylogenetic trees based on 16S ribosomal RNA (16SrRNA) sequences have shown that the genus Actinomyces is quite diverse, exhibiting polyphyletic branching into several clusters. The genera Actinomyces and Mobiluncus form a monophyletic clade in a phylogenetic tree constructed using RpoB, RpoC, and DNA gyrase B protein sequences. This clade is also strongly supported by a conserved signature indel consisting of a three-amino-acid insertion in isoleucine tRNA synthetase found only in the species of the genera Actinomyces and Mobiluncus. [6]

Pathology

Actinomycota are normally present in the gums, and are the most common cause of infection in dental procedures and oral abscesses. Many Actinomyces species are opportunistic pathogens of humans and other mammals, particularly in the oral cavity. [7] In rare cases, these bacteria can cause actinomycosis, a disease characterized by the formation of abscesses in the mouth, lungs, or the gastrointestinal tract. [8] Actinomycosis is most frequently caused by A. israelii, which may also cause endocarditis, though the resulting symptoms may be similar to those resulting from infections by other bacterial species. [9] [10] Aggregatibacter actinomycetemcomitans has been identified as being of note in periodontal disease, especially aggressive and localized form. [11]

The genus is typically the cause of oral-cervicofacial disease. It is characterized by a painless "lumpy jaw". Lymphadenopathy is uncommon in this form of the disease. Another form of actinomycosis is thoracic disease, which is often misdiagnosed as a neoplasm, as it forms a mass that extends to the chest wall. It arises from aspiration of organisms from the oropharynx. Symptoms include chest pain, fever, and weight loss. Abdominal disease is another manifestation of actinomycosis. This can lead to a sinus tract that drains to the abdominal wall or the perianal area. Symptoms include fever, abdominal pain, and weight loss. [12] Actinomyces species have also been shown to infect the central nervous system in a dog "without history or evidence of previous trauma or other organ involvement." [13]

Pelvic actinomycosis is a rare but proven complication of use of intrauterine devices. In extreme cases, pelvic abscesses might develop. Treatment of pelvic actinomycosis associated with intrauterine devices involves removal of the device and antibiotic treatment. [14]

Diagnosis

Actinomycosis may be considered when a patient has chronic progression of disease across tissue planes that is mass-like at times, sinus tract development that may heal and recur, and refractory infection after a typical course of antibiotics. [12]

Treatment

Treatment for actinomycosis consists of antibiotics such as penicillin or amoxicillin for 5 to 12 months, [15] as well as surgery if the disease is extensive. [12]

Species

The genus Actinomyces comprises the following species: [16]

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<i>Actinomyces naeslundii</i> Species of bacterium

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<span class="mw-page-title-main">Actinomycosis</span> Medical condition

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. gerencseriae. Infection can also be caused by Streptomyces somaliensis and Propionibacterium propionicus. The condition is likely to be a polymicrobial anaerobic infection.

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<i>Bacteroides fragilis</i> Species of bacterium

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<i>Eikenella corrodens</i> Species of bacterium

Eikenella corrodens is a Gram-negative facultative anaerobic bacillus that can cause severe invasive disease in humans. It was first identified by M. Eiken in 1958, who called it Bacteroides corrodens. E. corrodens is a rare pericarditis associated pathogen. It is a fastidious, slow growing, human commensal bacillus, capable of acting as an opportunistic pathogen and causing abscesses in several anatomical sites, including the liver, lung, spleen, and submandibular region. E. corrodens could independently cause serious infection in both immunocompetent and immunocompromised hosts.

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Capnocytophaga is a genus of Gram-negative bacteria. Normally found in the oropharyngeal tract of mammals, they are involved in the pathogenesis of some animal bite wounds and periodontal diseases.

Aggregatibacter actinomycetemcomitans is a Gram-negative, facultative anaerobe, nonmotile bacterium that is often found in association with localized aggressive periodontitis, a severe infection of the periodontium. It is also suspected to be involved in chronic periodontitis. Less frequently, A. actinomycetemcomitans is associated with nonoral infections such as endocarditis. Its role in aggressive periodontitis was first discovered by Danish-born periodontist Jørgen Slots, a professor of dentistry and microbiology at the University of Southern California School of Dentistry.

<span class="mw-page-title-main">Pathogenic bacteria</span> Disease-causing bacteria

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<span class="mw-page-title-main">Actinomycosis in animals</span> Bacterial disease mostly affecting cattle

Actinomycosis is an infection caused by a bacterium of the genus Actinomyces, usually Actinomyces bovis; the disease it causes has several common names. When it is a moveable tumour or lump on the jaw area, it is referred to as lump jaw; when it spreads into the hard bone of the jaw, it is referred to as big jaw; and when it affects the tongue, it is referred to as wooden tongue.

<i>Actinomyces israelii</i> Species of bacterium

Actinomyces israelii is a species of Gram-positive, rod-shaped bacteria within the genus Actinomyces. Known to live commensally on and within humans, A. israelii is an opportunistic pathogen and a cause of actinomycosis. 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 (1848–1926), who studied the organism for the first time in 1878.

Aggregatibacter is a genus in the phylum Pseudomonadota (Bacteria), which contains three species, namely:

Anaerobic infections are caused by anaerobic bacteria. Obligately anaerobic bacteria do not grow on solid media in room air ; facultatively anaerobic bacteria can grow in the presence or absence of air. Microaerophilic bacteria do not grow at all aerobically or grow poorly, but grow better under 10% carbon dioxide or anaerobically. Anaerobic bacteria can be divided into strict anaerobes that can not grow in the presence of more than 0.5% oxygen and moderate anaerobic bacteria that are able of growing between 2 and 8% oxygen. Anaerobic bacteria usually do not possess catalase, but some can generate superoxide dismutase which protects them from oxygen.

<i>Actinomyces bovis</i> Species of bacterium

Actinomyces bovis is a branching, Gram-positive, rod-shaped bacterium of the genus Actinomyces. It is the causative agent of lumpy jaw in cattle, and occasionally causes actinomycosis infections in humans. A. bovis normally populates the gastrointestinal tract of healthy ruminants, but is opportunistic in nature and will move into tissues through ulcerations or abrasions of the mucosa to cause infection. The disease occurs when there is physical damage to the tissue of the mouth, allowing the bacteria to colonize the deep tissue and bone, typically affecting the mandible and maxilla. Actinomycosis is pathognomonic for abscesses containing "sulfur" granules, and its colonies appear basophilic with club-shaped reaction products on a histological preparation. Lumpy jaw is commonly treated with broad-spectrum antibiotics with varying success, and can be a major economic loss for producers in countries where it is endemic. Because this organism is zoonotic, it is a human health concern and can cause granulomas, abscesses, skin lesions, and bronchopneumonia.

Actinomyces viscosus is a human and animal pathogen/pathobiont which colonises the mouths of 70% of adult humans. A. viscosus has a low level of virulence and is often mistaken with other actinomycetes.

References

  1. ↑ Harz CO. (1877–1878). "Actinomyces bovis, ein neuer Schimmel in den Geweben des Rindes" [Actinomyces bovis, a new mold from the tissues of cattle]. Deutsche Zeitschrift für Thiermedizin. 5: 125–140.
  2. ↑ Bowden, Geroge [sic] H. W. (1996), Baron, Samuel (ed.), "Actinomyces, Propionibacterium propionicus, and Streptomyces", Medical Microbiology (4th ed.), University of Texas Medical Branch at Galveston, ISBN   978-0-9631172-1-2, PMID   21413327 , retrieved 2020-06-04{{citation}}: CS1 maint: numeric names: authors list (link)
  3. ↑ Holt JG, ed. (1994). Bergey's Manual of Determinative Bacteriology (9th ed.). Williams & Wilkins. ISBN   0-683-00603-7.
  4. ↑ Petrova, Mariya I.; Lievens, Elke; Malik, Shweta; Imholz, Nicole; Lebeer, Sarah (2015). "Lactobacillus species as biomarkers and agents that can promote various aspects of vaginal health". Frontiers in Physiology. 6: 81. doi: 10.3389/fphys.2015.00081 . ISSN   1664-042X. PMC   4373506 . PMID   25859220.
  5. ↑ Sullivan, DC; Chapman, SW (2010), "Bacteria that masquerade as fungi: actinomycosis/nocardia", Proc Am Thorac Soc, 7 (3): 216–221, doi:10.1513/pats.200907-077AL, PMID   20463251.
  6. ↑ Gao, B.; Gupta, R. S. (2012). "Phylogenetic Framework and Molecular Signatures for the Main Clades of the Phylum Actinobacteria". Microbiology and Molecular Biology Reviews. 76 (1): 66–112. doi:10.1128/MMBR.05011-11. PMC   3294427 . PMID   22390973.
  7. ↑ Madigan M; Martinko J, eds. (2005). Brock Biology of Microorganisms (11th ed.). Prentice Hall. ISBN   0-13-144329-1.
  8. ↑ Bowden GHW (1996). Baron S; et al. (eds.). Actinomycosis in: Baron's Medical Microbiology (4th ed.). Univ of Texas Medical Branch. ISBN   0-9631172-1-1. (via NCBI Bookshelf).
  9. ↑ Lam, S; Samraj, J; Rahman, S; Hilton, E (April 1993). "Primary actinomycotic endocarditis: case report and review". Clinical Infectious Diseases. 16 (4): 481–5. doi:10.1093/clind/16.4.481. PMID   8513051.
  10. ↑ Adalja, AA; Vergis, EN (August 2010). "Actinomyces israelii endocarditis misidentified as "Diptheroids[sic]"". Anaerobe. 16 (4): 472–3. doi:10.1016/j.anaerobe.2010.05.003. PMID   20493959.
  11. ↑ Åberg, Carola Höglund; Kelk, Peyman; Johansson, Anders (2014-12-12). "Aggregatibacter actinomycetemcomitans: Virulence of its leukotoxin and association with aggressive periodontitis". Virulence. 6 (3): 188–195. doi:10.4161/21505594.2014.982428. ISSN   2150-5594. PMC   4601274 . PMID   25494963.
  12. 1 2 3 El Sahli, MD, MS. "Anaerobic Pathogens." Infectious Disease Module 2007. Baylor College of Medicine, 2007.
  13. ↑ Couto, SS; Dickinson, PJ; Jang, S; Munson, L (November 2000). "Pyogranulomatous meningoencephalitis due to Actinomyces sp. in a dog". Veterinary Pathology. 37 (6): 650–2. doi: 10.1354/vp.37-6-650 . PMID   11105955. S2CID   5619351.
  14. ↑ Joshi C, Sharma R, Mohsin Z. Pelvic actinomycosis: a rare entity presenting as tubo-ovarian abscess. Arch Gynecol Obstet. 2010 Feb;281(2):305-6
  15. ↑ "Actinomycosis: MedlinePlus Medical Encyclopedia". www.nlm.nih.gov. Retrieved 18 January 2016.
  16. ↑ Euzéby JP, Parte AC. "Actinomycetaceae". List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved June 17, 2021.
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