11/12/2012
Current SSTI Categorization
Skin and Soft Tissue Infections
Made Simple
Brad Frazee, MD
Alameda County Medical Center
Oakland, CA
Abscess
Purulent cellulitis
Nonpurulent cellulitis
Necrotizing Skin
& Soft Tissue Infection
Bugs
Bugs
Bugs
Drugs
Drugs
Drugs
Not: bite wounds, water-related infections, surgical/hospital-acquired infections
Abscess
Purulent Cellulitis
1
11/12/2012
Nonpurulent Cellulitis
Necrotizing Skin & Soft Tissue Infection
(NSTI)
Diagnostic approach to the
undifferentiated SSTI
Utility of ED ultrasound
Red, warm, tender…
First look for pus
fluctuance or
positive bedside ultrasound
+
Abscess
+/Purulent cellulitis
• Diagnosis:
unsuspected pus
• Procedural assistance:
localize pus for I&D
Nonpurulent cellulitis
or
NSTI
2
11/12/2012
Nationwide rise in ED visits for skin & soft
tissue infections 1993-2005
Abscess
Nonpurulent cellulitis
Necrotizing Skin
& Soft Tissue Infection
Bugs
Bugs
Bugs
Drugs
Drugs
Purulent cellulitis
CA-MRSA
1998
Drugs
Pallin, Annals EM 2008
Prevalence of CA-MRSA in cultureable SSTIs
(422 ED pts, August 2004)
7/13 (54%)
11/28 (39%)
4/20 (20%)
Overall
59 % MRSA
32/58 (55%)
43/58(74%)
24/47 (51%)
26/42 (62%)
17/25 (68%)
24/47 (51%)
MSSA 17%
23/32 (72%)
46/69 (67%)
Moran. NEJM 2006
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11/12/2012
Abscess
• Bugs
Abscess
• Drugs
– Staph. aureus (~½ CA-MRSA)
– Caveats:
• Abscesses due to IDU can be polymicrobial: oral flora
(Strep. milleri, anaerobes), S. aureus
– antibiotics not necessary in uncomplicated
abscesses
–
– Antibiotics reserved for purulent cellulitis &
complicated abscesses
• Perirectal/perianal abscess: GNRs
NO
NO
NO
NO
Maybe
NO
Yes
Purulent cellulitis? Antibiotics needed?
4
11/12/2012
Loop drainage…or no packing at all
Purulent cellulitis (culturable)
• Associated with abscess (incl. just a pustule),
ulcer, purulent wound
• Purulant focus can, and should, be opened
and cultured
Purulent cellulitis
Jeng. Medicine 2002
5
11/12/2012
Purulent cellulitis
• Bugs
– Staph. aureus (~ 1/2 MRSA)
– Strep. species almost never produce purulence,
so Strep. coverage is not needed
• Drugs
– TMP/SMX PO
– Vancomycin IV
– Doxycycline is a PO option
– Clindamycin is second line
Stevens. CID 2005
Talan. NEJM 2006
Jeng. Medicine 2002
Ultrasound in purulent cellulitis
can be misleading
6
11/12/2012
Purulent cellulitis
Abscess
Purulent cellulitis
Nonpurulent cellulitis
Necrotizing Skin
& Soft Tissue Infection
Bugs
Bugs
Bugs
Drugs
Drugs
Purulent cellulitis
Drugs
7
11/12/2012
Nonpurulent cellulitis
Nonpurulent cellulitis
(non-cultureable or diffuse)
• Drugs
• Bugs
– β-hemolytic strep.
• S. pyogenes (Group A Strep)
• Group B, G, C Strep
– Staph. aureus is uncommon (up to 11-25%)
• MRSA ~ 1%
Jeng. Medicine 2010
Stevens. CID 2005
Siljander. CID 2008
Gunderson. J Infect 2012
– 1st generation cephalosporins
• Cefazolin (Ancef) IV
• Cephalexin (Keflex) PO
– Anti-Staph penicillins
• Nafcillin IV
• Dicloxacillin PO
– No need for MRSA coverage
Jeng. Medicine 2010
Stevens. CID 2005
Erysipelas: a superficial, nonpurlent
cellulitis, typically toxic
Habif. Clin Derm 1996
8
11/12/2012
Nonpurulent cellulitis
…I think
Nonpurulent cellulitis
Review
?
Abscess
Purulent cellulitis
Necrotizing Skin
& Soft Tissue Infection
Nonpurulent cellulitis
?
Nonpurulent cellulitis
Abscess
+
purulent cellulitis
9
11/12/2012
NSTI diagnosis
Abscess
1
Nonpurulent cellulitis
Necrotizing Skin
& Soft Tissue Infection
Bugs
Bugs
Bugs
Drugs
Drugs
Purulent cellulitis
Diabetic foot ulcer…
potentially gone bad
•
•
•
•
High clinical suspicion
Pattern recognition
CT
OR
Drugs
2
Perineal infections (esp in ♂)
10
11/12/2012
3
3
SSTIs in IDU
4
Black tar heroin
SSTIs in IDU
Unexplained musculoskeletal
pain…potentially gone bad
Wound botulism
Strep. pyogenes NSTI
NSTI
11
11/12/2012
NSTI imaging
NSTI imaging
Definitive diagnosis & definitive
treatment are the same
12
11/12/2012
NSTI
NSTI
• Drugs
• Bugs
– Monomicrobial
•
•
•
•
Strep. pyogenes (Group A Strep.)
Clostridium – perfringens…novyi, sordelli
Vibrio vulnificus
CA-MRSA (USA 300)
•
•
•
•
Staph. of all kinds
Strep. of all kinds
Anaerobes of all kinds
Gram negatives
Pipercillin/tazobactam (Zosyn)
+
Vancomycin
+
Clindamycin
– Polymicrobial / synergistic
Antibiotic Review
β-lactams
Abscess
Purulent cellulitis
Bugs
Drugs
Nonpurulent cellulitis
Bugs
Drugs
Necrotizing Skin
& Soft Tissue Infection
Bugs
Drugs
Antibiotic
β-strep
MSSA
MRSA
Penicillin
✓
X
X
Unasyn, Zosyn IV
Augmentin PO
✓
✓
X
0
Methicillin
✓
✓
X
0
Nafcillin IV
dicloxacillin PO
✓
✓
X
0
✓
✓
X
0
Ceftiaxone
✓
✓
X
0
Quinolones
✓
✓
X
65 (40-94)
TMP-SMX
X
✓
✓
97 (83-100)
Tetra/doxycycline
X
X
✓
88 (89-91)
Clindamycin
✓
✓
✓
87 (89-91)
Vancomycin
✓
✓
✓
100 (99-100)
Linezolid
✓
✓
✓
96 (92-100)
Cefazolin IV
cephalexin PO
Mean MRSA
susceptibility (range)*
0
*Fridkin. NEJM 2006; Moran. NEJM 2006
1 DS TMP/SMX usually sufficient
Inducible clinda MRSA
resistance (+ D-test); TID
dosing; expensive
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