Updated: Aug 13, 2008
Many infectious and inflammatory diseases affect the skin and the oral mucosa. Actinomycosis is one such characteristic and persistent infection. Actinomycosis is a subacute, chronic, cellulitic invasion of the soft tissues that causes the formation of external sinus tracts that discharge sulfur granules. This process spreads unimpeded by traditional anatomic barriers after the endogenous oral commensal organisms invade the tissues of the face and neck. Actinomycosis may also spread to the pulmonary and GI systems.1
Actinomycosis is caused by various bacterial species of the actinomycete group. Usually, the disease is caused by Actinomyces israelii, an anaerobic gram-positive organism that enters the tissue through a break in the mucosa.2 The Actinomyces genus of bacteria includes other species that normally inhabit the oral cavity but are seldom pathogenic. Actinomycosis begins as an inflammatory soft tissue mass, which can enlarge into an abscesslike swelling, with penetration of the overlying skin and the development of recognizable draining fistulae.
The term actinomycosis is misleading. Because of the derivative term mycosis (from the Greek mykes), some believe that actinomycosis is a fungal infection, although it is not a fungal infection. Aktino referred to the radiating organism in the sulfur granule as ray fungus. Human actinomycosis was first described in the medical literature in 1857, although a similar disease in cattle had been described in 1826. In 1877, Bollinger found Actinomyces bovis in granules from cattle with a condition called lumpy jaw. In 1878, Israel discovered granules in human autopsy material and described actinomycosis in humans in 1885.3 Israel further discovered that Actinomyces species do not survive outside mammalian hosts and that they are not found exogenously in plants or soil.
Prior to the antibiotic era, actinomycosis was a common illness and easily recognized at clinical examination. However, the microbiologic features of the etiologic organisms were not fully clarified until the 1940s.4 The therapeutic outcome of surgical management was variable, and even if healing occurred, sequelae and complications were common.5,6 Actinomycosis often became lifelong, and death was not unusual. At the dawn of the antibiotic era, morbidity resulting from actinomycosis decreased, and a general lack of familiarity with the disease process resulted.7 Subsequently, diagnoses of actinomycosis were often delayed because of a lack of microbiologic techniques.
The eMedicine article Bacterial Mouth Infections also may be of interest.
The pathogen is in actinomycosis a filamentous bacterium (see Media File 1 and Causes). Historically, actinomycosis has been confused with a fungal disease because of its appearance and the slowly progressive nature of the lesions, which mimics mycotic illness. Confusion was so great that, for many years, some investigators placed Actinomyces species in an intermediate status between fungi and bacteria.2 The unique nature of the organism is the absence of a nuclear membrane, which places Actinomyces species among the higher prokaryotic bacteria. The lack of chitin and gluten, coupled with the presence of muramic acid in the cell walls and the absence of mitochondria, is another distinct feature.8
All species of Actinomyces are normal commensal inhabitants of the oral and buccal cavities in humans and certain other mammals. They cannot be classified as symbiotic organisms because they do not have a mutually beneficial relationship with their host. They are not true parasites because they usually do not cause harm to the host; however, they definitely assume a parasitic role when they result in an infection with an inflammatory tissue response. Similar to Mycobacterium tuberculosis, actinomycetes survive phagocytosis by host cells, and they may be characterized as facultative intracellular parasites.
Actinomycosis does not appear to be an opportunistic infection because actinomycosis is not common in patients who are immunosuppressed or in patients with AIDS. One of the authors has experience in producing a bone infection in animals that leads to osteomyelitis; however, actinomycosis could not be induced in the tibias and mandibles of rabbits. This outcome may have been the result of the avirulent nature of the organisms. Perhaps the presence of other infectious bacteria is required in addition to the Actinomyces species to initiate the infection in experimental models.9
The incidence of human actinomycosis has been decreasing in the United States. Weese and Smith10 reported prevalences of 1 case per 12,000 admissions in the 1930s and 1 case per 21,000 admissions in the 1950s. Bennhoff11 reported a prevalence of only 1 case per 63,000 admissions in the 1970s. Actinomycosis can still be found in inner-city populations of the United States.
Actinomycosis remains a problem in underdeveloped countries.12
No evidence of long-term morbidity is observed in patients with actinomycosis treated with antibiotics and surgical excision of the necrotic tissue.
Actinomycosis affects persons of all socioeconomic levels and all races, and actinomycosis is not limited to any single segment of the population.
A male-to-female predominance in a ratio of approximately 3:1 has been observed for actinomycosis.13 This predominance is postulated to reflect the greater likelihood for facial and oral trauma and the lack of oral hygiene in males compared with females.
The incidence of actinomycosis is higher in persons aged 30-60 years than in others, and actinomycosis is rare in children. This difference may reflect the increased incidence of periodontal disease in elderly individuals.
Constitutional symptoms of actinomycosis may include nonspecific complaints such as weight loss, coughing, chest pain, and fever. When actinomycosis involves the jawbones, it is usually associated with localized pain, swelling, and draining fistulas. Actinomycosis may mimic other bacterial osteomyelitis.
Consider actinomycosis infection in the differential diagnosis of any acute, subacute, or chronic cutaneous or soft tissue swelling of the face, head, or neck.
Actinomyces species are prevalent in the oral cavity. The bacteria are isolated from the interdental sulci, periodontal membranes, tonsillar crypts, and saliva.12 Poor oral hygiene and dental caries appear to be primary predisposing conditions for the development of actinomycosis. In addition, the presence of associated bacteria appears to be fundamental to the development of clinical infection (see Lab Studies).
Currently, 4 species are recognized in actinomycosis. In order of importance, they are A israelii, Actinomyces naeslundii, Actinomyces viscosus, and Actinomyces odontolyticus.1
Aspergillosis
Erysipelas
Leishmaniasis
Nocardiosis
Osteomyelitis
Brucellosis
Botryomycosis
Blastomycosis
Histoplasmosis
Toxoplasmosis
Osteomyelitis
Multiple myeloma
Central giant cell granuloma
Osteosarcoma
Fibrous dysplasia
Hodgkin lymphoma
Burkitt lymphoma
Bisphosphonate
Consider actinomycosis infection in the differential diagnosis of any acute, subacute, or chronic cutaneous or soft tissue swelling of the head, face, or neck. The Medscape Head and Neck Cancer Resource Center may be of interest.
The presence of associated bacteria in actinomycosis appears to be fundamental to the development of clinical infection (see Lab Studies). Therefore, antibiotic coverage should be aimed at all associated organisms in patients with actinomycosis. An aerobic environment is an unfavorable condition for the growth of Actinomyces species and thus halts the infection.16,19,20,21,22
With the combination of administering penicillin therapy and creating an aerobic envirorment with surgery, cure has become the rule rather than the exception.
Surgical management in actinomycosis has consisted of various treatment modalities, including excision of sinus tracts, drainage of the abscess cavities, removal of the bulky infected masses, and irrigation and curettage of the osteomyelitic bony lesions.
The abscesses of actinomycosis should be drained, or sinus tracts should be radically excised. With the combined use of penicillin and surgery, cure has become the rule rather than the exception.
An oral and maxillofacial surgeon should be consulted because the jaws are involved.
The goals of pharmacotherapy in the treatment of actinomycosis are to eradicate the infection, reduce morbidity, and prevent complications.
Actinomycosis therapy must cover all likely pathogens in the context of this clinical setting. Antibiotic selection should be guided by blood culture sensitivity whenever feasible.
Interferes with synthesis of cell wall mucopeptide during active multiplication, resulting in bactericidal activity against susceptible microorganisms.
Prolonged therapy, including >1 year, may be necessary.
Cervicofacial: 1-6 million U/d IV in divided doses q4-6h for 2-6 wk
Thoracic and abdominal: 10-20 million U/d IV in divided doses q4-6h (administer slowly) for 2-6 wk; administer penicillin VK thereafter
<1 week or <1.2 kg: 25,000 U IV q12h
1-4 weeks: 25,000 U q8h IV (1.2-2 kg) or q6h (>2 kg)
<12 year but > 1 month: for mild/mod disease use 25,000-50,000 U/kg/d IV divided qid; for severe disease use 250,000-400,000 U/kg/d IV in 4-6 divided doses
>12 years: Administer as in adults
Probenecid may increase effectiveness by decreasing clearance; tetracyclines are bacteriostatic, decreasing effectiveness of penicillins when administered concurrently
Documented hypersensitivity
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Caution in severe renal impairment (modify dosage), history of seizures, or hypersensitivity to cephalosporins; hemolytic anemia reported
Interferes with synthesis of cell wall mucopeptide during active multiplication, resulting in bactericidal activity against susceptible microorganisms. Has better GI absorption than penicillin G
2-4 g/d PO in 4-6 divided doses (best if 1 h ac or 2 h pc) for 6-12 mo
<1 month: Not established
>1 month: 15-62.5 mg/kg/d PO in 3-6 divided doses for 6-12 mo; not to exceed adult doses
Probenecid may increase effectiveness by decreasing clearance; tetracyclines are bacteriostatic, decreasing effectiveness of penicillins when administered concurrently
Documented hypersensitivity
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Caution in severe renal impairment (modify dosage), history of seizures, or hypersensitivity to cephalosporins; hemolytic anemia reported
Schaal KP, Schofield GM. Classification and identification of clinically significant Actinomycetaceae. In: Ortiz-Ortiz L, Bojalil LF, Yakoleff V, eds. Biological, Biochemical, and Biomedical Aspects of Actinomycetes. Orlando, Fla: Academic Press; 1984:505-20.
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actinomycosis, Actinomyces israelii, A israelii, inflammatory disease, bacterial infection, Actinomyces naeslundii, A naeslundii, Actinomyces viscosus, A viscosus, Actinomyces odontolyticus, A odontolyticus
Talib Najjar, DMD, MDS, PhD, Professor of Oral and Maxillofacial Surgery and Pathology, University of Medicine and Dentistry of New Jersey
Disclosure: Nothing to disclose.
Janet Fairley, MD, Professor and Head, Department of Dermatology, University of Iowa
Janet Fairley, MD is a member of the following medical societies: American Academy of Dermatology, American Dermatological Association, American Federation for Medical Research, and Society for Investigative Dermatology
Disclosure: Nothing to disclose.
Michael J Wells, MD, Associate Professor, Department of Dermatology, Texas Tech University Health Sciences Center
Michael J Wells, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, and Texas Medical Association
Disclosure: Nothing to disclose.
Drore Eisen, MD, DDS, Consulting Staff, Department of Dermatology, Dermatology Research Associates of Cincinnati
Drore Eisen, MD, DDS is a member of the following medical societies: American Academy of Dermatology, American Academy of Oral Medicine, and American Dental Association
Disclosure: Nothing to disclose.
Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University
Catherine Quirk, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology
Disclosure: Nothing to disclose.
Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology
Disclosure: Nothing to disclose.
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