diagnosis of actinomycosis

Last reviewed 01/2018


Making the diagnosis of actinomycosis is difficult. It should be suspected in patients with the following clinical 'warning signs'

  • indolent course
  • chronicity
  • mass-like features
  • development of sinus tracts (which can heal and re-form)
  • progression through tissue planes
  • refractory or relapsing infection after short course of antibiotics

A definitive diagnosis depends on isolating the organism from a clinical specimen.

Investigations which are useful in actinomycosis include:

  • blood test - usually non specific, may have anaemia, mild leucocytosis, raised ESR and CRP and alkaline phosphatase (in hepatic actinomycosis)
  • histopatholgy - presence of gram positive filamentous organisms and sulphur granules on histological examination is strongly supportive of a diagnosis of actinomycosis
  • microbiology - direct  isolation of the organism (either from a clinical specimen or from 'sulphur granules) provides a definitive diagnosis