Management of Carbuncles and Cellulitis

Key Characteristics and Treatment

A carbuncle is a localized collection of pus involving multiple adjacent hair follicles that requires incision and drainage, while cellulitis is a diffuse, spreading skin infection without pus collection that is treated primarily with antibiotics, as recommended by the Infectious Diseases Society of America 1, 2
The American College of Physicians suggests that cellulitis presents with erythema, warmth, and edema but no fluctuance, and is typically caused by bacterial invasion through broken skin, commonly involving streptococci and MRSA 1, 4
Incision and drainage is the cornerstone of treatment for all carbuncles, with systemic antibiotics being secondary, according to the Clinical Infectious Diseases guidelines 1, 2, 3

The Infectious Diseases Society of America recommends that surgical drainage is mandatory for carbuncles, with thorough evacuation of pus and probing to break up loculations 2, 3
Antibiotics are usually unnecessary for carbuncles unless fever or systemic signs of infection are present, as stated by the Clinical Infectious Diseases guidelines 1
The American College of Physicians suggests that antibiotics are the primary treatment for cellulitis, without need for surgical intervention, and recommends a 5-6 day antibiotic course for nonpurulent cellulitis 1, 4
Choose antibiotics active against streptococci for typical cases of cellulitis, such as cephalosporin, penicillin, or clindamycin, as recommended by the Infectious Diseases Society of America 1

Cellulitis is more likely to cause systemic symptoms and spread rapidly, and requires hospitalization if SIRS is present, altered mental status, hemodynamic instability, or concern for deeper or necrotizing infection, according to the Clinical Infectious Diseases guidelines 1, 3
The American College of Physicians recommends that cellulitis can progress to life-threatening complications if untreated, and emphasizes the importance of prompt treatment 1

Do not treat carbuncles with antibiotics alone without drainage, as this will fail, and do not perform incision and drainage on cellulitis, as there is no pus to drain, as warned by the Infectious Diseases Society of America 1, 2
Obtain culture of pus to guide antibiotic therapy if systemic treatment is needed for carbuncles, especially with multiple lesions or recurrent infections, as recommended by the Clinical Infectious Diseases guidelines 1, 3
Extend antibiotic treatment beyond 5-6 days only if infection has not improved within this timeframe for cellulitis, as suggested by the American College of Physicians 1, 4