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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

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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

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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

• Antibiotic susceptibility: TMP/SMX, clinda, doxy• Pathogenicity

• Spreads within communities � outbreaks of skin & soft tissue infections• Native American communities • Prison inmates• Sports teams

2003-2004N=137Young (<60)

18% homeless27% IDU

CA-MRSA Oakland ED study

Frazee et al. Annals Emerg Med. 2005

CA-MRSA Oakland ED study culture results

Nares cultureN=137

MSSA12

MRSA28 (20%)

Negative97

87% USA 300 clone

Main predictor of MRSA (OR 29): furuncle

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Multicenter National Study of SSTIsEMERGEncy ID NET

OV-UCLAGrady

Charity

Maricopa

UNM

OHSU

UMissouri

Hennepin

Carolinas

Temple

Bellevue

Prevalence of MRSA across US 422 ED Patients with SSTI (August, 2004)

7/13 (54%)

24/47 (51%)

24/47 (51%)

26/42 (62%)

11/28 (39%)

43/58(74%)

46/69 (67%)

23/32 (72%)

17/25 (68%)

32/58 (55%)

4/20 (20%)59%

MSSA 17%Moran. NEJM 2006

CA-MRSA risk factors & epidemiology

• Risk factor data inconsistent • prior CA-MRSA infection (or close contact)

• Risk groups (in which outbreaks have occurred)• Prison inmates• Contact sport teams• HIV-positive• American Indian

• Importance of fomites (dressings, surfaces)

MRSA Antibiotic susceptibility

Antibiotic Mean susceptibility (%) Range (%)

Methicillin 0 0

Erythro 18 6-47

TMP-SMX 97 83-100

Tetracycline 88 89-91

Clindamycin 87 89-91

Rifampin 98 67-100

Vancomycin 100 99-100

Linezolid 96 92-100

Fluouroquinolones 65 40-94

Inducible clindamycin resistance (+ D-test)

Fridkin. NEJM 2006 Moran. NEJM 2006

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Uncomplicated abscess

• Surgical treatment• Strongly consider no Abx• If Abx, cover MRSA• Doxy or TMP/SMX alone

• Pure cellulitis• Impetigo

• Cover GAS*• Ceph. ** +/- TMP/SMX

TMP/SMX + Ceph. or Amox/clav***or

Clindamycin alone

Vanco +/- Clindaor

Vanco + Pip/tazo***

Skin & soft tissue infectiontreatment algorithm

• Consider surgical treatment• Cover CA-MRSA & GAS

• Complicated abscess (a/b cellulitis, fever, etc)• Infected wound, foot ulcer, etc• Immunocompromised host

po IV

*GAS = Group A strep.**Ceph.= cephalexin

*** if Gram neg. pathogensuspected

Abscess incision & drainage

Abscess I & Doptions for anesthesia and sedation

• Local - bupivicaine ring block• Regional anaesthesia – ultrasound guidance• Nitro-nox

• Conscious sedation - fentanyl + midazolam• Short acting deep sedation in ED

• Methohexitol (+ fentanyl)• Propofol (+ fentanyl)

• General anesthesia in OR

Local Ring Block

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How do you manage this thing?

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Abscess I&Dpost I&D antibiotics

• Literature • Definitive studies still pending• What seems clear: abx for “uncomplicated

abscess” are of no benefit

• Often invoked to justify abx: • Diabetes• > 5 cm• Significant “surrounding cellulitis”

Rutherford. Lancet 1970 Rajendran. Antimicrob Agents Chemother 2007

Llera. Ann EM 1985 Duong. Ann EM 2009

Nankin. Ann EM 2007

CA-MRSA uncomplicated abscess:are antibiotics needed?

NO NONO

MaybeYes

CA-MRSA decolonization?

• Very little data for CA-MRSA

• History of multiple furuncles• Multiple cases in single household

• Nasal 2% mupirocin• Chlorhexidine (Hibicleanse) washes - axilla and groin

• Consider: rifampin + TMP/SMX or doxycycline

Other types of CA-MRSA infections:necrotizing fasciitis

• 14 adults, Harbor-UCLA• 6 IDU• 12 monomicrobial for CA-MRSA

• All USA 300, PVL+• 0% mortality

• 1 case report of CA-MRSA nec fasc in a 5 d/o infant

Miller. NEJM 2005 Dehority. Pediatr Infect Dis J 2006

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Other types of CA-MRSA infections:pyomyositis

Panaraj. CID 2006 Ruiz. NEJM 2005

• Spontaneous abscess of large muscles (e.g. thigh)

• Risk factors: diabetes & AIDS

• Formerly rare in non-tropical countries

• Reports increasing adults and children

Other types of CA-MRSA infections:septic arthritis (SA) & osteomyelitis (OM)

• Pediatric referral centers:• OM: MRSA isolated in 50-66% of cases• SA: “ 19-47% “

• Adult SA in the ED (UCSF & Highland)• MRSA in 6/12 cases • Median synovial fluid WBC in MRSA cases: 15K

Arnold. J Ped Ortho 2006 Kaplan. CID 2005

Frazee. Annals EM 2009

Time 0 Time + 15 hrs

FebruaryHealthy 31 y/o manc/o cough (blood tinged)

114/69 105 18 99.0 SpO2 100%

Returns w/ worsening hemoptysis & SOB

94/60 130 26 93.3 87% on RA15L O2 � 7.08 / 63.7 / 262 WBC 1.8 (50% bands)

Intubated, EGT, levo, Zosyn, vanco…

Dies T + 55 hrSputum & blood cx’s -> MRSA (US300)

PSI class 1D/c on Levo

Case 2 Other types of CA-MRSA infections:necrotizing pneumonia

• Increasing reports in children and adults• Almost always - in setting of influenza-like illness• Sometimes - history of SSTI in pt or close contact

• “Necrotizing” = cavitation and hemoptysis• Leukopenia and sepsis syndrome • � mortality

• Empiric vanco or linezolid for severe CAP during flu season?

Francis. Clin Infect Dis 2005 MMWR 2007 (56)

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Case 3

42 y/o man c/o painful right arm and shoulder x 3 days. Hx of IDU (“skin popping heroin”). No other trauma or bite.

PMH: HCV, HBV, HIV negative, hx of multiple abscesses

PE: uncomfortable, but NADT 38.0 R 22 HR 120 BP130/60

1540 135

45Differential: 12% bands

75% PMN

• Chemistries normal• CXR: normal

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Case 2 - course

• Immediate antibioitics: Unasyn + clinda + vanco• Immediate surgical consultation • To OR 3 hrs after presentation, for suspicion

necrotizing infection

• OR findings: massive subQ edema; fat necrosis; muscle and fascia necrosis

• Pt died 2 hours post op from refractory shock

Necrotizing soft tissue infections (NSTIs) -definition

• 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

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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

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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:

• Bullae• Crepitus• Cutaneus sensory deficit• Skin necrosis

• Very characteristic in IDU’s• tense edema � trunk• � � WBC

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NSTIs presentation

• Fever: ~20-80%• � WBC: ~85% (WBC > 20 in over 50%)• Shock or organ dysfunction: 0-40%

NSTI: diagnostic modalities

• Plain x-ray for gas: ~ 30% sensitive• CT scan for gas: more sensitive than plane film• MRI

• Ultrasound• Strep. rapid antigen test• Bedside fascia inspection• � CPK in myonecrosis

NSTI of footsoft tissue gas on plain x-ray

Necrotizing fasciitis ultrasound findings

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Necrotizing fasciitisMRI findings

• Fascial enhancement • Thickening • Adjacent fluid

• Lacks specificity

NSTI: diagnostic decision rules

• Wall, et al• WBC > 14 + Na <135

• LRINEC Score (Wong, et al)

• CRP• WBC• Hb• Na• Cr• Glu

Wall. J Am Coll Surg 2000Wong. Crit Care Med 2004

Numerical scoring system

NSTIdiagnostic approach

• INDEX OF SUSPICION is the key

• IMMEDIATE surgical consultation � IMMEDIATE exploration and debridement• Time to OR is only correlate of survival that is

modifiable• Low threshold for operation (analogous to traditional

approach to appendicitis)• Systemically ill patient still goes to OR • Be forceful with inexperienced surgical consultants

NSTIrisk factors for poor outcome

(15-30% mortality)

• Age > 60, # of organ system failure, extent of infection, elevated Cr…

• Delay to operation >12-24 hrs appears to quadruple mortality• Admission to a nonsurgical service• Negative bedside FNA

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NSTIspattern recognition

1. IDUs: beginning at injection site on extremities �trunk; marked edema; � WBC; case clusters

2. Feet � up the leg, in diabetics

3. Perineum � lower abd, usually in men (Fournier’s)

4. Head & neck, dental source (Lugwig’s)

5. GAS-associated: normal host w/ unexplained severe

soft tissue pain; leukocytosis or fever; case clusters

NSTIsantibiotic therapy

• Vanc + clindamycin + pipercillin / tazo

• Linezolid + pipercillin / tazo

Worried about a NSTI? Worried about a NSTI?

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Skin & soft tissue infectionstake home messages

1. Look for pus (ED ultrasound) & drain it!

2. Uncomplicated drained abscesses do not require antibiotics

3. Wherever you are…CA-MRSA is there

4. Always consider NSTI

5. Suspicion of NSTI requires immediate surgery

Cellulitis Bonus Slides

Erysipelas

Recommended therapy:Penicillin alone

Bee sting with lymphangitis