Actinomycosis – Cause, Transmission, Treatment

Definition :

            It is a chronic infection manifesting both granulomatous and suppurative features; and usually involves soft tissues and occasionally bone.


Types :

There are three types:

  1. Cervicofacial,
  2. Thoracic,
  3. Abdominal.


Cervicofacial actinomycosis :

  • About 2/3rd of cases are cervicofacial.
  • It involves mandible, overlying soft tissues, parotid gland, tongue and maxillary sinuses.
  • Secondary spread to other areas of head may occur.

Historical background:

  • J Israel in 1877, isolated an organism belonging to genus Actinomyces.
  • Historically, such organisms were considered to be fungi and are associated with a disease in humans analogous to lumpy jaw disease of cattle.

At least three types of Actinomyces have been related to the disease.

  1. israelii: It is responsible for disease in humans.
  2. bovis: It is responsible for disease in cattle, but rarely in humans.
  3. baudetti: It is responsible for diseases in cats and dogs.
  • Several species of Actinomyces are found as normal saprophytes in human oral cavity; including: A. israelii, A.naeslundii, A. propionicus, and A. eriksonii.
  • Except for A. Israelii, the role of these organisms in the disease is not established.
  • These are endogenous in origin, and are found in
  • Tonsillar crypts,
  • Salivary and dental calculus,
  • Mucosa of oropharyngeal and gastrointestinal regions.
  • Pathogenecity is attributed to changes in local or general environment

predisposing factors of osteomyelitis

Characteristic features:

  • It is now recognized that Actinomyces are not fungi; but are Gram positive, microaerophilic, nonsporeforming, and non-acid-fast bacteria.
  • Like Nocardia and Mycobacteria, Actinomycetes, share characteristics of both bacteria and fungi. However, they are not sensitive to antifungal drugs


  • Organisms gain entry into soft tissues directly or by extension from bone through Periapical, Periodontal lesions, Fractures, or Extraction sites.
  • When established, infection spreads without regard to fascial planes and typically appears on cutaneous rather than mucosal surfaces.

infection of dental origin

Clinical features:

  • Patients present with the following:
  • Soft or firm tissue masses on the skin; which have purplish, dark red, oily areas with occasional small zones of fluctuation.
  • Spontaneous drainage of serous fluid containing granular material. These granules are yellowish substances called sulfur granules, and represent colonies of bacteria.
  • Regional lymph nodes are occasionally enlarged.
  • Trismus: Not common; unless secondary infection.
  • Pyrexia: Usually the patient is not febrile; and does not feel ill.
  • Microscopically, it shows closely packed branching filaments 1 μ in diameter.


The common findings are

  • Radiolucent areas of varying sizes, and delay in healing of extraction sites
  • Periostitis
  • Diffuse mandibular radiolucencies and marked bone sclerosis.
  • Sequestra formation is occasionally present.

 Laboratory studies:

  • ESR and WBC Count may be slightly elevated.
  • Whenever, a firm mass/infections, which does not respond to conventional antibiotic therapy, then actinomycosis, mycosis, mycobacterial infection, and neoplasms should be considered in diagnosis.

Differential diagnosis :

The following conditions should be considered:

  • Parotitis,
  • parotid tumors,
  • cervical tuberculosis, and
  • pyogenic OML.

Diagnosis is based on Culture and sensitivity testing, and Biopsy.


In the past, many therapeutic agents and techniques were used including:

  • Iodides,
  • Radiation,
  • Incision and drainage, and
  • Excision of soft tissues and bone.
  • Currently, iodides and radiotherapy are considered to be ineffective.

 Incision and drainage:

  • All abscesses, regardless of how small they are, should be surgically disrupted with a hemostat and all loculations penetrated.
  • Hospitalization is required; because, antibiotics are administered parenterally: in high doses,  for protracted periods of time, shows temporary resolution and recurrence.
  • Penicillin is the antibiotic of choice. The dose depends on severity of the disease. 10 to 20 million units
  • daily for 3 to 4 months; 3 million units IV every 4 hourly for 2 weeks or longer.
  • Subsequently; 0. 5 gm probenecid orally four times daily. This daily 2 gm probenecid will increase blood
  • concentration of penicillin 2 to 3 folds by inhibiting its renal excretion.

treatment of actinomycosis, incision and drainage

In patients allergic to penicillin:

  • Tetracycline (especially Minocycline 250 mg 4 times daily for 8 to 16 weeks, may be prescribed(Martin, 1985).
  •  Erythromycin 500 mg 4 times daily for 6 months. The dosages and durations for therapy used are effective for most infections and result in temporary resolution, only to be followed by recurrence. Therefore, high doses for extended periods are recommended.
  • Sequestrectomy and saucerization may be necessary.
  • Follow-up: Radiographs are taken periodically to monitor changes in bone.

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