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Home , Boil, Bullous impetigo, Cellulitis, Erysipelas, Hot tub folliculitis, Impetigo

Cellulitis and Soft Tissue

Sally Williams MD : A very common

 25 cases per 1000 patient years  More common in men, obese patients  60% occurs in the lower extremities  74% handled as outpatients  82% of patients have just a single episode  High cause of hospital readmissions Cellulitis: definition

 A nonspecific term that includes a large collection of & soft tissue infections  Can include: – (the most common cellulitis) – Cellulitis associated with – Gangrenous cellulitis – Secondary infection of pre-existing skin – Cutaneous involvement of systemic illness Normal Skin Structure Locations of Skin Infections

and : upper  Erysipelas and cellulitis: lower epidermis and , furuncles, “” : deep dermis and hair follicles  Necrotizing : deep, next to muscle Microbiology of Cellulitis

 The vast majority are strep and staph  More unusual etiologies: – Cat bite: – Dog bite: Capnocytophaga (splenectomized) – Rat bite: Streptobacillus – Fresh water: – Salt water:Vibrio and Mycobacterium marinum – Hot tubs: Pseudomonas Classic hot tub Mix and Match Impetigo

 Very common in kids  Has appearance of “ colored crusts”, often on face  Etiology is always staph or strep  Treat with topical bactroban or oral abx  is always staph, forms vesicles and bullae  Impetigo quite infectious! Impetigo

 Erysipelas: Clinical Features

 Often of rapid onset  Etiology is always streptococcal  Often preceded by , and groin pain (for lower extremity cellulitis)  Often after a few days  Usually has lymphangitic streaking  Almost always worsens in appearance before improving on Classic Leg Cellulitis Facial Cellulitis Erysipelas continued

 Risk factors for erysipelas/strep cellulitis: – Leg – Previous leg – – Previous breast surgery (for arm and breast cellulitis) – Tinea pedis (NOT ) – Uncontrolled Natural History of Erysipelas

 Is almost always preceded by fevers, chills, and rapid increase in  ALWAYS gets “worse” before better – Will extend outside drawn “borders”  Almost always has and elevated wbc  Can take WEEKS to get better if has underlying edema, history of surgery etc  Will often Is this Cellulitis?? Is this Cellulitis? Rule #1

 There is no entity of “BILATERAL lower extremity cellulitis”.  These are usually all chronic stasis  True cellulitis almost always has: – 1. Elevated wbc – 2. Erythema above the knee – 3. Fever, and often preceding chills – 4. Often “patches” of cellulitis on upper thigh Rule #2: Please do not culture this Wound Cultures

 Never culture a chronic open wound – The wounds will ALWAYS be colonized with multiple – A wound without PMNs on gram stain is probably not an infected wound – Countless unnecessary courses of antibiotics are used, predisposing pts to C difficile  If you can unroof an or express from something then culture that Rule #3: Vancomycin not needed for cellulitis without

 Classic cellulitis is streptococcal  Strep releases a streptozyme to dissolve layer underneath the skin, causing rapid spread. – Multiple different strep species may cause cellulitis (A,B,C,F,G) – Strep almost always causes lymphangiitis  Staph cellulitis is almost always associated with a boil or abscess Staph skin boils Cellulitis continued

 Treatment of non-boil, non-nec fasc cellulitis is strep targeted- Rx or ceftriaxone  As soon as they let the leg down will get bigger, redder, hotter – this is NOT treatment failure, just dependent edema.  We need to prepare patients that the leg may look abnormal for months in some cases  History of MRSA irrelevant if looks streptococcal – Please do NOT use vancomycin for diffuse cellulitis Cellulitis Treatment

 Most heavy weight people “fail” oral antibiotics due to insufficient blood levels – may need a course of iv antibiotics or high bioavailability oral .  “Failing” keflex is not a reason to use vancomycin – they just need iv cefazolin  Strep itself is easy to kill but the infection causes a lot of “leftover damage” as the lymph system is often damaged. We have to prepare patients for slow improvement Summary: Leg Cellulitis

 Occurs most commonly in the obese or persons with a history of surgery in that leg  Warn them of “worsening” when they start ambulating, leg will get redder, hotter  If you use po antibiotic, need very high doses, e.g. 1-1.5g cephalexin qid  If they truly “failed” high dose keflex could consider oral levoflox, has high blood levels MRSA: Not a (courtesy of GiantMicrobes.com) MRSA Epidemiology

 First described in 1961  Previously hospital associated, now widely community acquired since 2002  Most C.A. MRSA strains are US 300 and carry the PVL (panton valentine leukocidin) gene, causes  C.A. most commonly skin/soft tissue infections, less likely bacteremia Staphylococcal Cellulitis & Boils Risk Factors

 Young age  Immunocompromised  Contact sports  Crowded conditions  Sharing towels, sheets etc  Prior antibiotics, especially quinolones Antibiotics for Staph skin boils- do they help?

 Randomized studies are conflicting  Many studies show no benefit to antibiotics after  The studies that did show a benefit related a small one with using TMP-S + I&D.  Drainage is likely 95% of the battle-if the pt has extensive induration oral Rx may be helpful, especially if >2 cm. Antibiotic treatment for MRSA

 Vancomycin for the hospitalized patient, Daptomycin also useful but expensive  resistance up to 33%  Bactrim is still sensitive >90% of the time  Doxycyline resistance actually quite low  Linezolid effective, but has rare drug interactions – Serotonin syndrome <.1%, still black box warning  Dalbavancin/: likely to not be used due to >$1000 per dose of antibiotic Does antibacterial soap help?

 Antibacterial Soap? You Can Skip It, Use Plain Soap and Water (FDA November 2017)  Most contain triclosan, a pesticide – No proven efficacy – Potential to cause antibiotic resistance – Potential to affect hormones  Hand sanitizers ARE effective Recurrent skin lesions

 Most common in young overweight women  Essentially acquisition is bad luck, can be very difficult to eradicate  Nasal mupiricin for household sometimes effective, with mass washing  For severe cases Bactrim suppression for a few months is an option

 Uncommon severe infection  Etiologies may be: – Streptococcal (most common) – Polymicrobial –usually associated with gut flora (e.g. perirectal abscess, Fourniers) or trauma – Staphylococcal –usually post op, needs to be differentiated from necrotizing staph soft tissue infection which is very common. Strep necrotizing fasciitis Clinical Picture of Necrotizing Fasciitis

 These patients are very ill – febrile, hypotensive, tachycardic, delerious  Pain out of proportion to exam  Cutaneous anesthesia  Very rapid spread  May have skin bullae (often black), ecchymoses, usually edema Example of Leg Nec Fasc Necrotizing Fasciitis

 WBC almost always very high or very low  Cr usually about 2, pt often in toxic shock  Nec fasc is a SURGICAL EMERGENCY  Antibiotics are targeted toward strep, staph or polymicrobic- Vanco + Piptazo  Clindamycin is added as inhibits toxin production, but surgery is life saving How does Necrotizing fasciitis/ toxic shock happen?

 BAD LUCK  It requires a toxin producing strain of strep (rare) often in the setting of uncontrolled DM  AND a lack of immunity to the toxin (also rare)  IVIG is often used with toxic shock to give patient a large “antibody load” -someone in the large pool of donors likely has an antibody to the toxin Summary: Skin Infections

 Cellulitis is common and is usually strep  Most cellulitis gets worse before better  Boils are almost always staph/MRSA and need to be drained to achieve cure  Chronic is incredibly common and should not be mistaken for cellulitis  Nec fasciitis is rare and pts are very ill IDSA SSTI guidelines Antibiotic humor Superbugs coming…