1 Skin & Soft Tissue Infections 2009 Bradley W Frazee, MD, FACEP Dept of Emergency Medicine Alameda County Medical Center - Highland Hospital Associate Clinical Professor of Medicine UCSF Skin & Soft Tissue Infections (SSTI) • Community associated-MRSA (CA-MRSA) • Abscess management • Necrotizing soft tissue infections (NSTI) SSTIs diagnostic approach: first look for pus! Redness, warmth, tenderness… fluctuance or positive bedside ultrasound Abscess* Cellulitis or NSTI* *Surgical diseases + SSTIs Utility of ED ultrasound • Diagnosis: unsuspected pus • Procedural assistance: localize pus pocket for I&D
16
Embed
Skin & Soft Tissue Infections 2009 - UCSF CME · Skin & Soft Tissue Infections 2009 Bradley W Frazee, MD, FACEP Dept of Emergency Medicine Alameda County Medical Center - Highland
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Skin & Soft Tissue Infections2009
Bradley W Frazee, MD, FACEPDept of Emergency Medicine
Alameda County Medical Center - Highland HospitalAssociate Clinical Professor of Medicine
UCSF
Skin & Soft Tissue Infections (SSTI)
• Community associated-MRSA (CA-MRSA)
• Abscess management
• Necrotizing soft tissue infections (NSTI)
SSTIsdiagnostic approach: first look for pus!
Redness, warmth, tenderness…
fluctuance orpositive bedside ultrasound
Abscess* Cellulitisor
NSTI**Surgical diseases
+
SSTIsUtility of ED ultrasound
• Diagnosis:unsuspected pus
• Procedural assistance:localize pus pocket for I&D
2
Case #1the old “spider bite”
40 y/o woman c/o a “spider bite” on leg. Onset 3 d/a. Hx of same 1 mo/a. Notes husband had similar “bite”.No PMH or MedsNo IDU
Afebrile….
?!!??!
“Spontaneous furuncle”
CA-MRSA skin infectionsNationwide rise in ED visits for
SSTIs…attributable to CA-MRSA
Pallin, Annals EM 2008
3
The story of CA-MRSA• Hospital-associated MRSA (HA-MRSA)
• present since 60’s • Multiresistant, SCCmec I-III• Pts presenting from community with HA-MRSA
infections had risk factors (recent hospitalization, SNF, HD…)
• CA-MRSA • mid 1990’s • Community onset MRSA infection - no risk factors• Children in U.S. (pneumonia…deaths); Native
Americans; Australia; France…• Explosion of skin & soft tissue infections
CA-MRSA
• Distinct genotype• SCCmec IV (an allele w/ PCN resistance gene)• USA 300 (a pulsed field gel type)
• Panton-Valentine Leukocidin (PVL; a cytotoxin)• Distinct phenotype
• Histologic findings: extensive tissue necrosis, thrombosed vessels, abundant bacteria with few inflammatory cells
• Clinical definition: rapidly progressive soft tissue infection, eventually associated with systemic toxicity, fatal without surgical therapy
NSTIs - bacteriology
• 1/3 -3/4 polymicrobial
• Staphylococcus - aureus (incl MRSA), epidermidus• Nonclostridial anaerobes (oral anaerobes)• Non group A Streptococcus• Clostridium - perfringens and others• Group A Streptococcus
• Most common monomicrobial culprit• Gram negatives
11
Devitalized tissue+
Synergistic infection(Clostridium)
InvasiveGAS
+/- host susceptibility
NSTI
NSTIs -simplified pathophysiology
Exotoxins,cytokines
Nec fascMyonecrosisFournier'sStrep TSS
Rapid bacterial growth & spread
NSTIsrisk factors
• IDU • 30-56% of cases in urban series• Typically, long hx of IDU / skin popping
• Diabetes• Foot & lower extremity most common
• Post trauma and surgery • Peripheral vascular disease• Malnutrition & alcoholism
NSTIs epidemic in N. California IDUs
(occurs throughout Western U.S.)
Bosshardt. Arch Surg 1996
Chen. Clin Inf Dis 2001
Davis, CA107 cases presenting to ED59 (55%) IDU
NSTIsclusters in IDUs
• San Francisco, 1999• 5 cases of Clostridial myonecrosis in IDUs in 5 weeks,
3 roommates• Molecular linkage & Clostridia cultured from paraphernalia
• United Kingdom, spring 2000• 88 cases; 45% mortality
• Mean WBC 64,000• C perfringens, Clostridium novyi
• Oakland CA, 2001 • > 40 cases presenting to ED; ~20% mortality• Clustered, assoc. w/ black tar heroin
Bangsberg. Arch Int Med 2002 MMWR 2000Lonergan. J Emerg Med 2004
12
Case 4
36 y/o woman c/o 2d calf pain and swelling. Vague hx of recent minor trauma. No bite or wound.
PMH: NIDDM MED: glyburideHab/Soc: no IDU
Afebrile BP 130/70 HR 95 R 20
WBC 12.2
NSTI due to Group A Streptococcus
• Classic scenario: • In children following varicella
• Usually:
• Adult victims without risk factors • Community onset• Portal of entry: none (50%) or trivial (blunt trauma)
• Clusters described • GAS is spread among close contacts• Consider post-exposure prophylaxis
• Causes Strep. Toxic Shock Syndrome w/ high mortality
NSTIs presentation
• Average 3-4 d of sx prior to presentation• Pain >> skin signs (common but not universal)• Erythema (77%), induration (43%), swelling, warmth• Classic signs frequently absent: