Patients with ABSSSIs present with erythema, warmth, edema, and pain over the affected site.1 Systemic features of infection may follow, their intensity reflecting the severity of infection. Common pathogens include Streptococcus pyogenes, Staphylococcus aureus and other Gram-positive bacteria.1,2,4
Image available at: https://ercare24.com/cellulitis-emergency
Cellulitis/erysipelas are diffuse, non-purulent skin infections characterized by spreading areas of redness, edema, and/or induration. The red area of the skin tends to expand and the conditions are associated with swelling, tenderness, warmth and fever, and common pathogens are Streptococcus pyogenes and other β-hemolytic streptococci.
Image courtesy of Gregory Moran, M.D, via the Centers for Disease Control and Prevention
Major cutaneous abscesses are characterized by a collection of pus with surrounding granulation within the dermis or deeper tissues that is accompanied by redness, edema, and/or induration. They present as painful swelling with induration and central fluctuance.
Image courtesy of https://www.clinimed.co.uk/wound-care/symptom-management/management-of-exudate-and-infection
Wound infections are characterized by purulent drainage from a wound with surrounding redness, edema, and/or induration. Wound infections are associated with pain, tenderness and ulceration and may be caused by Staphylococcus aureus and are occasionally polymicrobial.
Comprehensive diagnosis of SSTIs often starts with a clinical history and findings from physical examination that help assess the severity of an infection. Although diagnosis of SSTIs is based on clinical presentation, microbiologic investigation is recommended in certain situations; for example, routine Gram-stain and culture of purulent material from carbuncles and abscesses are recommended by the Infectious Disease Society of America (IDSA).11 A precise diagnosis guides the decision on prompt and appropriate treatment.3,11
Radiological examination and imaging aid investigations of deep tissue infections to assess site and size of infection and any vascular involvement which can guide surgical drainage procedures.1,3 For patients with severe infection or comorbid conditions, common laboratory investigations can include complete blood count, C-reactive protein level, and liver and kidney function tests.1,3
Diagnosis of SSTIs relies primarily on clinical examination and findings, although microbiological investigation confirms the cause in over 60% of cases, suggesting a predominance of Gram-positive bacteria.2 The approach to diagnosis should follow the principles set out in guidelines from the Infectious Diseases Society of America (IDSA) on SSTIs, which involves assessment of severity, and recommends management approaches based on whether infections are purulent or non-purulent.
The IDSA guidelines on SSTI define mild, moderate and severe disease based on the presence of systemic signs and symptoms of infection and other patient specific variables.11
