What is botryomycosis?
Botryomycosis is a chronic inflammatory response to a bacterial infection involving the skin and sometimes internal organs.
Botryomycosis is a rare condition, with few reported cases worldwide. Because it is so rare, there is confusion in the literature over the classification and definition of the illness. Some authors have suggested that cutaneous botryomycosis is a subtype of pyoderma vegetans, and propose these two conditions should be classified together.
The name is misleading; botryomycosis is a bacterial infection rather than a fungal infection. "Botryo" is a latin term for "bunch of grapes". Other authors have suggested that actinomycosis and botryomycosis should be classified under the single term ‘granular bacteriosis’.
What causes botryomycosis?
Some form of trauma, surgery, or the presence of a foreign body usually precedes infection. Botryomycosis is more likely to occur in patients with immunodeficiency, such as those with HIV infection, alcoholism, cystic fibrosis, prolonged corticosteroid use and diabetes mellitus.
What are the clinical features of botryomycosis?
Botryomycosis most commonly affects the skin and presents as subcutaneous nodules, abscesses, large verrucous lesions, ulcers, fistulae and sinuses with purulent discharge. The lesions generally develop over several months and may drain pus. The pus may contain small yellow “grains” similar to the sulphur granules of actinomycosis.
Infection may extend to the subcutaneous tissues, muscles, and bones.
It is rare for botryomycosis to affect internal organs. Lungs are the most commonly infected and usually there is a predisposing factor such as surgery or impaired immunity.
How is the diagnosis of botryomycosis made?
Botryomycosis can be difficult to diagnose. Diagnosis depends on high clinical suspicion along with microscopy/culture to identify typical bacteria and grains in swabs taken of pus or in skin biopsy.
The sulfur granules seen in botryomycosis contain bacteria surrounded by an eosinophilic matrix with club-like projections. This histologic appearance is commonly referred to as the Splendore-Hoeppli phenomeno and can be seen using gram stain, giemsa stain or silver stain.
What is the treatment for botryomycosis?
Botryomycosis is treated with:
- Long-term antibiotics. The choice of antibiotics depends on the bacteria identified and includes trimethoprim-sulfamethoxazole, oral clindamycin, cephalexin, doxycycline and erythromycin.
- Surgical drainage and debridement
- Laser vapourisation