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Actinomyces Israelii

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Actinomyces israelii

Morphology

• Size, shape and motility o Actinomyces israelii is small, filamentous bacteria. It is a bacillus and is normally seen in short chains. Actinomyces is non motile.3 o Some cultures may produce colonies made up of short angular branching filaments or small rough compact colonies with no filaments 6 o Macrocolonies on blood agar and Brain- Heart infusion agar are .5-3 mm in diameter. These colonies are circular to irregular, lobate and white.6 o Structures called fimbriae on the cell surface that are similar to, but smaller than flagella, and made of protein located on the bacterial cell surface allow A. israelii to grow in biofilms.3
• Genetics o The genome of A. israelii is currently being sequenced, using the Actinomyces israelii F0345 strain for comparative genome analysis.3 o Actinobacteria are categorized by their high GC content in DNA, about 60%. 6
• Cell envelope & sporulation o Actinomyces israelii species is gram-positive, cast-forming, non–acid-fast, and non–spore-forming. 8
• Mode of reproduction o Slow-growing by binary fission. On an enriched solid medium such as brain-heart infusion agar in an environment of 37°C. 11
• Specimen collection o A specimen is collected from pus aspirated from abscess (usually in the neck or pelvic area) and is incubated for a minimum of 5 days. 4
• Identification o The most effective way to identify is by Gram stain. Specimen stains purple for gram positive. 4 o The gram stain should also reveal its filamentous nature.
• Diagnosis of disease o Actinomyces israelii frequently causes Actinomycosis.2 o Pus tests and biopsys may be done to test for Actinomyces israelii.
Transmission
• Ecological niche o Actinomyces israelii is carried by humans. It is a natural component of the human gastrointestinal and oral flora. 3 o It is also commonly found in soil. A. israelii have a significant role in the recycling of nutrients.3
• Mode of transmission o Source of infection Is endogenous as the normal habitat is the oral cavity of man including tonsillar crypts and dental calculus. 6 o Infection happens through breach of the mucosal barrier during various procedures, aspiration, or pathologies such as diverticulitis.1 o Pelvic actinomycosis is a rare but proven complication of intrauterine devices. an accumulation of the bacteria around a foreign object such as an IUD creates a biofilm infection. 5
• Incubation period o The incubation period in the host varies from several days to several years.7
• Immune response o Actinomyces israelii survives host defenses such as phagocytes.3
Infection
• Pathogenesis o A. israelii connect to surfaces, such as tissues and teeth, as well as to one another, forming the filamentous colonies, or biofilms, that allow the cells to avoid phagocytosis. 3 o Disruption of the mucosal barrier is a pivotal step in the pathogenesis.11 o Bacteria can cause abscesses with granules.11
• Body systems affected o Oral-Cervicofacial Actinomycosis: This is the most common type of actinomycosis. The most common cases involve a soft tissue swelling, abscesses, or mass lesions. Pyogenic abscesses may develop, with the formation of interconnecting sinuses that contain granules. The most common location is the perimandibular region. The most commonly occurring lesion occurs at the angle of the jaw, causing “lock jaw”. o Thoracic Actinomycosis: May lead to pulmonary infection. The symptoms are mild fever, chest pain, weight loss and less commonly hemoptysis. Lung tissue is destroyed, sinus tracts develop and invasion of the ribs or vertebrae may occur. o Abdominal Actinomycosis: initiated by a perforation of the intestinal mucosa. The symptomatology is determined by the location of the lesion and the organs involved. Symptoms associated with abdominal actinomycosis include fever, weight loss, change in bowel habits, abdominal pain or sensation of mass. o Pelvic Actinomycosis: Pelvic actinomycosis may be associated with any type of intrauterine contraceptive device. Symptoms include fever, weight loss, abdominal pain, and abnormal vaginal bleeding or discharge. Pelvic masses, and tubo-ovarian abscesses may occur. 11
• Consequences if untreated o Left untreated, A. israelii can cause growth of enormous lesions or abscesses. o In extreme cases, Actinomycosis can cause organ failure in the region/ cavity affected.
Treatment and Prevention
• Treatment and drug resistance o Treatment of Actinomycosis caused by A. israelii is usually with antibiotics for a long period of time, up to a year.3 o Penicillin is the drug of choice for treating actinomycosis.11 o Amoxicillin, erythromycin, clindamycin, doxycycline, and tetracycline are also used.7 o In some cases, surgical removal of infected tissue is necessary.
• Prevention o Primary prevention includes appropriate oral hygiene, regular dental care, and careful cleansing of wounds, including human bite wounds, can prevent infection.7 o Use of a copper IUD instead of a plastic IUD can prevent pelvic actinomycosis in women.5 o The use of antibiotics to combat A. israelii is a method of secondary prevention of actinomycosis.
• Epidemiology o Actinomycosis occurs worldwide, with likely higher prevalence rates in areas with low socioeconomic status and poor dental hygiene.8 o The availability of antibiotics has greatly improved mortality rates due to A. israelii o Actinomycosis can affect people of all ages, but most cases are reported in young to middle-aged adults. 8

References
1.) "Actinomyces israelii." RedOrbit. N.p., n.d. Web. 23 Mar. 2013. < http://www.redorbit.com/education/reference_library/health_1/infectious_diseases/2584104/actinomyces_israelii/ >.
2.) "Actinomyces israelii - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 23 Mar. 2013. .
3.) "Actinomyces israelii NEUF2011 - MicrobeWiki." MicrobeWiki. N.p., n.d. Web. 23 Mar. 2013. .
4.) Casin, I, M Ortenburg, and JJ Denis. "[Actinomyces israelii. Methods of isolat... [Pathol Biol (Paris). 1984] - PubMed - NCBI." National Center for Biotechnology Information. NCBI, n.d. Web. 23 Mar. 2013. .
5.) Evans, DT. "Actinomyces israelii in the female genital tr... [Genitourin Med. 1993] - PubMed - NCBI." National Center for Biotechnology Information. N.p., n.d. Web. 23 Mar. 2013. .
6.) Holt, John G.. "Actinomyces Israelii." Bergey's manual of determinative bacteriology. 9th edition ed. Baltimore : Williams & Wilkins, 1994. 662-665. Print.
7.) "Red Book: Actinomycosis." Unbound Medicine | Medical & Nursing Apps for iPad, iPhone, Android, Windows Phone. N.p., 12 July 2012. Web. 23 Mar. 2013. .
8.) Roque , Manolette, and Roy Hampton. "Actinomycosis in Ophthalmology ." Medscape Reference. N.p., 20 Apr. 2012. Web. 23 Mar. 2013. .
9.) Roy, Sampurna. "Actinomycosis." Histopathology-india. N.p., n.d. Web. 23 Mar. 2013. .
10.) Saltz, Joel . "Actinomyces." Microbiology Newsletter 15.30 (1996): n. pag. Johns Hopkins Microbiology. Web. 23 Mar. 2013.
11.) Gut - BMJ Journals N.p., n.d. Web. 23 Mar. 2013. .

Resources for practitioners
- Holt, John G.. "Actinomyces Israelii." Bergey's manual of determinative bacteriology. 9th edition ed. Baltimore : Williams & Wilkins, 1994. 662-665. Print.
- Saltz, Joel . "Actinomyces." Microbiology Newsletter 15.30 (1996): n. pag. Johns Hopkins Microbiology. Web. 23 Mar. 2013.

Resources for patients
- Roque , Manolette, and Roy Hampton. "Actinomycosis in Ophthalmology ." Medscape Reference. N.p., 20 Apr. 2012. Web. 23 Mar. 2013. .
- "What Is Actinomycosis? What Causes Actinomycosis?." Medical News Today: Health News. N.p., n.d. Web. 23 Mar. 2013. .

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