Diagnosis of actinomycosis

Diagnosis

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)
• histopathology - the 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

Note - actinomycosis has often been called the 'great pretender' of head and neck diseases, reflecting the fact that the symptoms are not specific and may be found in other, much more common conditions.

Reference:

1. Wong VK, Turmezei TD, Weston VC. Actinomycosis. BMJ. 2011;343:d6099