skin and soft tissue infections - university of iowa · abscess furuncle carbuncle importance of...

Ben Appenheimer, MD

Assistant Professor

Division of Infectious Diseases

4/2/19

*No disclosures or conflicts of interest

SKIN AND SOFT TISSUE INFECTIONS

OBJECTIVES

• Understand the difference between purulent and non-

purulent skin and soft tissue infections (SSTIs)

• Understand how this difference affects microbiology

and treatment

• Learn how to identify necrotizing fasciitis and

understand the basics of initial treatment

• Understand the evidence behind treatment of purulent

skin and soft tissue infections

POLL EVERYWHERE

• Text BenA860 to 22333 for interactive polling

• When the questions come up, simply text the

letter associated with your answer to that same

number (22333)

Skin and Soft Tissue Infections

PurulentNon-Purulent

Erysipelas Cellulitis Necrotizing

FasciitisAbscess Furuncle Carbuncle

Importance of distinction:

• Affects likely microbiology, treatment, and follow upPublic Health Image Library, CDC

NON-PURULENT SSTI:

CELLULITIS/ERYSIPELAS

Erysipelas

• Generally refers to infection limited to upper dermis

• Some use it synonymously with cellulitis

• Well-demarcated, rapid onset fevers, chills, erythema

• Almost exclusively caused by beta-hemolytic Strep

https://www.uptodate.com/contents/image?imageKey=ID%2F110605&topicKey=ID%2F110529&source=outline_link&search=cellulitis&selectedTitle=2~150

http://healthh.com/wp-content/uploads/2014/05/erysipelas-pictures-2.jpg

Non-Purulent


Fasciitis

NON-PURULENT SSTI:


Cellulitis

• Infection involving deeper dermis and subcutaneous fat

• Border is less demarcated, onset is more indolent

• Essentially evaluated and treated the same as erysipelas

• Coverage for beta-hemolytic Strep is required

• Whether MSSA coverage is needed is debated


Non-Purulent


Fasciitis

https://www.uptodate.com/contents/image?imageKey=ID/110605&topicKey=ID/110529&source=outline_link&search=cellulitis&selectedTitle=2~150

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwic39nAgdzVAhVI4YMKHX6PDwMQjRwIBw&url=http://steveinmexico.blogspot.com/2015/11/&psig=AFQjCNFkkRmshIF5Yi1nl0ogBIiGFjyrFw&ust=1502981720512092

NON-PURULENT SSTI:


Microbiology

• Predominantly beta-hemolytic Strep species

• i.e. Group A Strep (aka Strep pyogenes)

• Staph aureus is a much less common cause of non-purulent cellulitis

• IDSA Guidelines:

• ‘Combined data from specimen cultures, serologic studies, and other methods suggests that the vast majority of these infections arise from Streptococci’

Open Forum Infectious Diseases, Volume 3, Issue 1, 1 January 2016, ofv181

WHAT COVERAGE IS NEEDED FOR

ERYSIPELAS AND CELLULITIS?

• Historically we have worried about beta-hemolytic Strep, MRSA, and MSSA for skin and soft tissue infections

• Strep coverage is always required for non-purulent SSTIs

• Therefore, when deciding on antibiotics for non-purulent skin and soft tissue infections, the questions are:

• Do I need MRSA coverage?

• Do I need MSSA coverage?

WHAT COVERAGE IS NEEDED?

Is MRSA coverage needed?

What about in the inpatient setting?

• One hospital looked at response to oxacillin or cefazolin

in treatment of ‘non-culturable’ cellulitis

• 116/121 (95.8%) had clinical response without MRSA

coverage

Cephalexin

alone

Cephalexin +

TMP/SMX

95% CI P value

Pallin et al 2013 60/73 (82%) 62/73 (85%) -9.3% to 15% 0.66

Moran et al 2017 165/193 (85.5%) 182/218 (83.5%) -9.7% to 5.7% 0.50

CONSIDERING MRSA COVERAGE

IN CELLULITIS

• Purulence noted

• Penetrating trauma

• Including IV drug use

• Open wound or underlying hardware

• Evidence of MRSA infection elsewhere

• Lack of response to beta-lactam therapy

• Not necessarily based on appearance

• Severe systemic symptoms

Clinical Infectious Diseases, Volume 59, Issue 2, 15 July 2014, Pages e10–e52,

WHAT COVERAGE IS NEEDED?

What about MSSA?

• Studies cited above have included Strep and MSSA coverage in the control groups

• No much data for regimens only covering Strep

• Per guidelines, ‘many clinicians could include coverage against MSSA (weak recommendation, low evidence)’

• Some first line regimens per IDSA guidelines only cover Strep

My take:

• For presentations that are classic for erysipelas (ie rapid onset, well-demarcated erythema, no signs of deep fluid collection, no trauma or wound), I often focus my coverage on Strep pyogenes with either penicillin or amoxicillin

• For cellulitis, would not be faulted for including MSSA coverage

Clinical Infectious Diseases, Volume 59, Issue 2, 15 July 2014, Pages e10–e52,

NON-PURULENT SSTI:


Guideline recommended oral treatment for mild

infections

Dosing Resistance rate of

Group A Strep

Notes

Penicillin VK 500mg QID 0% Narrowest spectrum

Amoxicillin 500mg TID 0% 3x daily dosing

Cephalexin 500mg QID 0% Only needed if MSSA coverage desired

Dicloxacillin 500mg QID 0% Only needed if MSSA coverage desired

Clindamycin 300mg QID ~5% Some resistance, some Staph coverage

Non-Purulent


Fasciitis

What about TMP/SMX or doxycycline?• Efficacy against beta-hemolytic Strep is not well established

NON-PURULENT SSTI:


Guideline recommended oral treatment for mild

infections

Non-Purulent


Fasciitis

Dosing Resistance rate of

Group A Strep

Notes

Penicillin VK 500mg QID 0% Narrowest spectrum

Amoxicillin 500mg TID 0% 3x daily dosing

Cephalexin 500mg QID 0% Only needed if MSSA coverage desired

Dicloxacillin 500mg QID 0% Only needed if MSSA coverage desired

Clindamycin 300mg QID ~5% Some resistance, some Staph coverage

NON-PURULENT SSTI:


Guideline recommended IV treatment for

moderate non-purulent SSTI

Resistance rate

of Group A Strep

Notes

Penicillin G 0% Narrowest spectrum, continuous infusion

Cefazolin 0% 3x daily dosing, covers MSSA

Ceftriaxone 0% Once daily, broader than needed (ie GNR coverage)

Clindamycin ~5% Occasionally covers Staph

Non-Purulent


Fasciitis

NON-PURULENT SSTI:


Guideline recommended IV treatment for

moderate non-purulent SSTI

Resistance rate

of Group A Strep

Notes

Penicillin G 0% Narrowest spectrum, continuous infusion

Cefazolin 0% 3x daily dosing, covers MSSA

Ceftriaxone 0% Once daily, broader than needed (ie GNR coverage)

Clindamycin ~5% Occasionally covers Staph

What about Vancomycin?• Relatively weak Strep drug. Technically covers it, but not well

Non-Purulent


Fasciitis

Medicine (Baltimore). 2010 Jul;89(4):217-26. doi: 10.1097/MD.0b013e3181e8d635.

https://www.ncbi.nlm.nih.gov/pubmed/20616661

DURATION OF THERAPY

• Uncomplicated cellulitis:

• IDSA Guidelines: ‘Recommended duration of antimicrobial therapy is 5 days, but treatment should be extended if the infection has not improved within this time period (strong recommendation, high quality evidence)

• Evidence: RCT showed If symptoms have improved by 5 days, 5 day course is as effective as a 10 day course

• Clinical manifestations did not need to be fully resolved

• Caveat: this study used only levofloxacin

Non-Purulent


Fasciitis

Arch Intern Med. 2004 Aug 9-23;164(15):1669-74.


ADJUNCTIVE THERAPIES FOR

CELLULITIS

• Limiting edema

• Leg elevation

• Look for portal of entry

• Fissuring, scaling, or maceration between toes

• Onychomycosis, psoriasis, etc

• Prednisone

• Per IDSA, ‘can consider 40mg PO x 7 days in non-diabetic patients’

• RCT with 108 patients showed more rapid clinical resolution without change in relapse or recurrence rates

• Haven’t seen this done clinically very often

Scand J Infect Dis. 1997;29(4):377-82.


CELLULITIS MIMICS

• Stasis dermatitis

• Erythema, hyperpigmentation,

serous drainage, desquamation

• Nontender, no systemic signs,

usually bilateral

• Contact dermatitis

• Lymphedema

Cleveland Clinic Journal of Medicine. 2012 August;79(8):547-552

• 38 y/o with h/o untreated HCV who presents to the

ED with left periorbital swelling, erythema, and pain.

This started shortly after a fall where he hit his eye

on a well pump. Over the next 24 hours he noticed

progressive swelling, severe pain, and purplish

discoloration. He was febrile up to 104.5,

disoriented, and lethargic. His WBC was 20.1.

Maxillofacial CT is seen below. What empiric

regimen should be started?

• Answers on following

slide






• Affects likely microbiology, treatment, and follow up

NON-PURULENT SSTI:

NECROTIZING INFECTIONS

Necrotizing fasciitis

• Severe, rapidly progressing, life threatening soft tissue

infection

• Often starts with skin lesion from minor trauma

• Exam may show blisters, purple discoloration, crepitus

• Patients are usually ‘toxic’

• Surgical emergency

Non-Purulent


Fasciitis

https://www.jyi.org/2002-may/2002/5/23/when-bacteria-go-bad-the-case-of-necrotizing-fasciitis

Guberman and Faroqi. Podiatry today, volume 24, issue 9, September 2011.

https://www.jyi.org/2002-may/2002/5/23/when-bacteria-go-bad-the-case-of-necrotizing-fasciitis

NON-PURULENT SSTI:

NECROTIZING INFECTIONS

Microbiology

• Variable

• Type I Necrotizing fasciitis

• Polymicrobial (as in Fournier’s gangrene or odontogenic infections)

• Mix of aerobic and anaerobic bacteria (including Clostridium perfringens)

• Type II necrotizing fasciitis

• Monomicrobial

• Strep pyogenes infection

• Staph aureus

Non-Purulent


Fasciitis

NON-PURULENT SSTI:

NECROTIZING INFECTIONS Non-Purulent


Fasciitis

Clinical manifestations

• Initial presentation is similar to cellulitis

• Progresses to include systemic toxicity

• High fevers, disorientation, lethargy

• Skin can become firm, necrotic (purple/black/gray),

blister, and have crepitus

• Pain out of proportion to exam

• Very high mortality with Strep pyogenes

• 30-70%

• Those who survive often have significant morbidity

NON-PURULENT SSTI:



Fasciitis

Diagnosis

• Definitive diagnosis is with surgery

• ‘dishwater gray’ tissues

• Radiographs (CT is best) showing subcutaneous

air are suggestive of necrotizing SSTIs

• If high suspicion, should not wait for imaging prior to

surgical consult

• This is a relatively late finding

NON-PURULENT SSTI:



Fasciitis

Treatment

• Immediate surgical consult for emergent

operative debridement

• Often require multiple re-explorations

• Initially cover with broad spectrum antibiotics

• As previously mentioned, microbiology can be variable

• Need to cover Strep, Staph (including MRSA), resistant GNRs,

and anaerobes

• Once the organism is known, tailor therapy

accordingly

NON-PURULENT SSTI:



Fasciitis






• Affects likely microbiology, treatment, and follow up

DEFINITIONS (PURULENT)

Abscess

• Collections of pus within the dermis and deeper skin tissues

• Painful, tender, and fluctuant

Furuncles

• Infections of the hair follicle with pus down to the subcutaneous tissues

• Aka ‘boils’

Carbuncles

• Infection involving several adjacent follicles


Microbiology

• Most common: Staph aureus (MSSA and MRSA)

• Occasionally see Strep, GNRs but we don’t often

empirically cover for these

Antibiotics

• Empiric therapy should target MRSA and MSSA

with narrowing after susceptibilities

• TMP/SMX or doxycycline

• Vancomycin

PURULENT SSTI

CID 2014:59 (15 July)

https://www.uptodate.com/contents/image?imageKey=ID%2F53261&topicKey=ID%2F110529&source=outline_link&search=abscess&selectedTitle=4~126

UIHC ANTIBIOGRAM

TREATMENT OF

UNCOMPLICATED ABSCESSES

Group Clindamycin TMP/SMX Placebo

Cured/

Total

%

(95% CI)

Cured/

Total

%

(95% CI)

Cured/

Total

%

(95% CI)

Intention to treat 221/266 83.1%

(78.3-87.9)

215/263 81.7%

(76.8-86.7)

177/257 68.9%

(62.9-74.9)

Population available

for evaluation

221/238 92.9%

(89.3-96.4)

215/232 92.7%

(89.0-96.3)

177/220 80.5%

(74.8-86.1)

N Engl J Med 2017; 376:2545-2555

TREATMENT OF ABSCESSES

BMJ Open. 2018 Feb 6;8(2)

Treatment Failure in 1 month

OR 0.58 (0.37,0.90)

Recurrence or new lesion

within 1 month

OR 0.48 (0.3, 0.77)

Recurrence or new lesion > 1

month

OR 0.64 (0.48, 0.85)

Favors Antibiotics Favors Control

https://www.ncbi.nlm.nih.gov/pubmed?term=29437689

TO PACK OR NOT TO PACK

Abscesses < 5cm, immunocompetent Packing

N = 23

No packing

N= 25

RR, 95% CI P value

Re-intervention at 48 hours 4 5 1.3, (0.4 – 4.2) 0.72

Use of ibuprofen in first 48 hrs (600mg pills) 2.29 1.97 0.12

Use of oxycodone/APAP (pills) 3.1 0.91 0.03

Acad Emerg Med. 2009 May;16(5):470-3.


TAKE HOME POINTS

• Most non-purulent skin and soft tissue infections are due

to beta-hemolytic Strep and empiric coverage should be

targeted at these organisms

• Use beta-lactam antibiotics

• MRSA coverage is not necessary for non-purulent skin

and soft tissue infections

• Unless there is penetrating trauma or open wound

• Relatively short course treatment can be considered for

uncomplicated cases (ie 5 days)

• Be wary of ‘bilateral cellulitis’

TAKE HOME POINTS

• If concerned for necrotizing fasciitis, call surgery and

cover broadly

• Imaging can show subcutaneous air but this is a late

finding and is not sensitive for detecting nec fasc

• There is increasing evidence that patients benefit from

anti-MRSA antibiotics after I & D

• TMP/SMX and doxycycline have highest susceptibility

rates

• There is some question whether packing small abscesses

after I&D provides any significant benefit

QUESTIONS?

skin and soft tissue infections - university of iowa · abscess furuncle carbuncle importance of...

Documents