Cellulitis describes a deep infection of connective tissue, usually skin and subcutaneous tissues, in which there is obvious oedema. Erysipelas is a form of cellulitis
- some authors state that Group A beta haemolytic streptococcus (Streptococcus pyogenes) is the major cause of cellulitis whereas others state that cellulitis is most frequently caused by Streptococcus pyogenes or Staphylococcus aureus
- Staphylococcus aureus is a minor cause of the classic erysipelas
- Streptococcus pyogenes is the major agent of erysipelas, but also Staphylococcus aureus may be the causative micro-organism
- microbiological spectrum of cellulitis is wider than erysipelas including not only the mentioned staphylococci and streptococci, but also other Gram-positive and Gram-negative micro-organisms, including anaerobic bacteria
Cellulitis presents as a hot, raised, tender area of skin whose margin is less well demarcated than in erysipelas. Often, the patient is systemically unwell with fever and rigors. An abrasion usually allows the infective organism to enter the skin.
Investigations:
- full blood count
- blood cultures if appropriate
- swab analysis
Treatment is with systemic antibiotics, for example, oral penicillin V plus flucloxacillin (or erythromycin alone) or co-amoxiclav alone. If cellulitis is severe then management may require parenteral benzylpenicillin plus flucloxacillin OR co-amoxiclav alone.
Key points (2):
- exclude other causes of skin redness (inflammatory reactions or non-infectious causes)
- consider marking extent of infection with a single-use surgical marker pen
- offer an antibiotic. Take account of severity, site of infection, risk of uncommon pathogens, any microbiological results and MRSA status
- infection around eyes or nose is more concerning because of serious intracranial complications
- *a longer course (up to 14 days in total) may be needed but skin takes time to return to normal, and full resolution at 5 to 7 days is not expected
- do not routinely offer antibiotics to prevent recurrent cellulitis or erysipelas
Reference:
- Phoenix G, Das S, Joshi M. Diagnosis and management of cellulitis. BMJ. 2012 Aug 7;345
- Public Health England (June 2021). Managing common infections: guidance for primary care