dermatologic disorders
Cellulitis
Etiology of Cellulitis
Themost common causes of cellulitisare Streptococcus pyogenes Staphylococcus aureus Cellulitis is most often caused by group A beta-hemolytic streptococci (eg,S. pyogenes) orS. aureus. The skin barrier is usually compromised. Streptococci cause diffuse, rapidly spreading infection because enzymes produced by the organism (streptokinase, DNase,hyaluronidase) break down cellular components that would otherwise contain and localize the inflammation. Staphylococcal cellulitis is typically more localized and usually occurs in open wounds or Cutaneous Abscess . © Springer Science+Business Media This photo shows the focal redness and swelling of the lower leg, usually accompanied by warmth and tenderness, characteristic of focal cellulitis. The clinician has marked the border of the cellulitis with a pen, to facilitate recognition of spread or resolution. Note the line of redness extending up the thigh due to lymphangitis. © Springer Science+Business Media This photo shows the focal erythema and swelling, usually accompanied by warmth and tenderness, characteristic of focal cellulitis. Note the clinician has marked the border of the cellulitis with a pen, to facilitate recognition of spread or resolution. © Springer Science+Business Media (MRSA-USA300) is the predominant community strain of MRSA in the United States (community-associated MRSA [CA-MRSA]) ( Etiology reference ). If Less common causes of cellulitisare Group B streptococci (eg,S. agalactiae) in older adults with diabetes Gram-negative bacilli (eg,Haemophilus influenzae) in children Pseudomonas aeruginosain patients with diabetes or neutropenia, hot tub or spa users, and patients who are hospitalized Human and Mammal Bites may result in cellulitis and are often polymicrobial; . Immersion injuries in warm salt water may result in cellulitis caused by Noncholera Vibrio Infections . may become infected by opportunistic organisms, including gram-negative bacteria (such as Proteeae Infections , Risk factors include skin abnormalities (eg, trauma, ulceration, fungal infection, other skin barrier compromise due to preexisting skin disease), which are common among patients with Chronic Venous Insufficiency and Post-Thrombotic Syndrome or 1.Lakhundi S, Zhang K: Methicillin-resistantStaphylococcus aureus: Molecular characterization, evolution, and epidemiology.Clin Microbiol Rev31:e00020-18, 2018. doi: 10.1128/CMR.00020-18 