2.2.5 Furuncle/Carbuncle

The bacterial skin infection either spreads via autoinoculation (from nose or throat) or via exogenous transfer. The site of entry is the follicle ostium of the terminal hair-, the sebaceous gland- or vellus hair follicle. The transfer of bacteria mostly occurs from the nostrils, armpits, inguinal areas and rima ani. It may be smeared to other sites from the nostrils via the finger nails. Specific strains can produce furuncle / carbuncle out of an impetigo such as staph.aureus having the panton-valentine- leukozidine gene (about 60% of cases). Relapses of staph.aureus in skin infections are three times more frequent.

Initially a firm painful nodule appears, then it turns into a fluctuant abscess with central necrotic plug and is accompanied often by a surrounding oedema, a lymphangitis and lymphadenitis. It usually ends in a spontaneous rupture and drainage of the pus. It remains first an ulceration followed later by a yellow-brown crusts. The carbuncle is an even stronger infection with more pain, often starting with shivering, then fever and the danger of bacteraemia. If present on or around the nose, sinusoidal thrombosis or sepsis can occur.

In case of carbuncle: leucocytes, CRP, glucose, electrophoresis.

The histological pictures show severe inflammation with accumulation of neutrophils and macrophages within and in the surrounding the follicular canal with destruction of follicle and dermal collagen and other adnexal structures. In case of a carbuncle, fistular structures on serial sections can be detected. Massive macrophages in organizing the surrounding tissue and later scaring.

Prevention is associated with skin care, not over-washing with changing the skin microbiota into dysbiosis, avoiding autoinoculation and considering underlying diseases, diabetes mellitus, obesity, immuno-incompetence.

Therapy is usually

• Incision when fluctuation starts and continuous drainage with tamponade. Bed rest depending on localisation, elevation of involved area (face: talking, chewing forbidden).

• Systemic antibiotics for carbuncle and all furuncles in case of mid-face lesions and high-risk patients: penicillinase-resistant penicillins (oxacillin), alternatively erythromycin. Culture and sensitivity, since resistance is common and adjustments are needed.

• Topical: mechanical manipulation should be avoided. Wet antimicrobial dressings (clioquinol, povidone-iodine) can be applied, no topical antimicrobials except mupirocin. An incision should be in most cases be considered. There is evidence that body wash with chlorhexidine or octenidine together with mupirocin for the nose can prevent relapses. povidone-iodine highest antimicrobial action and most safe agent.