Management of Skin and Soft Tissue Infections: DNB Presentation Structure

Slide-by-Slide Architecture (60 minutes total)

Opening: Clinical Case Vignette (5 minutes)

Present a complex SSTI case with images
MCQ #1 (Difficult): "A 45-year-old diabetic presents with rapidly spreading erythema, bullae, and hypotension. Blood cultures show gram-positive cocci in chains. Which pathogen is LEAST likely responsible?"
- Forces differentiation between streptococcal vs. staphylococcal presentations
- Addresses the critical distinction that MRSA is an unusual cause of typical cellulitis 1

Section 1: Classification & Diagnosis (10 minutes)

Key Teaching Points:

Purulent vs. non-purulent distinction is clinically crucial 1: Primary treatment of cellulitis is antimicrobials, whereas purulent collections require drainage with antimicrobials having a subsidiary role
Erysipelas vs. cellulitis: Upper dermis/superficial lymphatics vs. deeper dermis/subcutaneous fat 1
Avoid routine cultures for typical cellulitis 1; reserve blood cultures and tissue sampling for:
- Malignancy
- Severe systemic features (high fever, hypotension)
- Unusual exposures (immersion injury, animal bites)
- Neutropenia or severe immunodeficiency

MCQ #2 (Difficult): "Which patient with cellulitis REQUIRES blood cultures and tissue biopsy?"

Tests understanding of when diagnostic workup escalates beyond clinical diagnosis

Section 2: Antibiotic Selection Principles (15 minutes)

For Typical Cellulitis (Non-purulent):

β-lactam monotherapy is recommended in the absence of abscess, ulcer, or purulent drainage 1:

Oral options: penicillin, amoxicillin, cephalexin, dicloxacillin, clindamycin
IV options: cefazolin, oxacillin (successful in 96% of cases) 1

MRSA Coverage - When to Add:

Coverage for MRSA is prudent ONLY in specific circumstances 1:

Penetrating trauma (especially IV drug use)
Purulent drainage present
Concurrent MRSA infection elsewhere
NOT for typical cellulitis - prospective data shows β-lactams successful in 96% 1

MRSA-active options 1:

IV: vancomycin, daptomycin, linezolid, telavancin
Oral: doxycycline, clindamycin, SMX-TMP
Dual coverage (streptococci + MRSA): clindamycin alone OR SMX-TMP/doxycycline + β-lactam

MCQ #3 (Difficult): "A 28-year-old IV drug user presents with cellulitis and purulent drainage. Which regimen provides appropriate empiric coverage?"

Tests understanding of when dual coverage is warranted vs. β-lactam monotherapy

Section 3: Duration of Therapy (10 minutes)

Present the evidence hierarchy:

Uncomplicated cellulitis: 5 days is as effective as 10 days if clinical improvement occurs by day 5 1
- This is the most actionable, evidence-based duration recommendation
Most bacterial SSTIs: 7-14 days 1
- From IDSA guidelines for general SSTIs
Recent data challenges longer durations 3, 4:
- 2025 pediatric trial showed guideline-concordant prescriptions (≤5 days for cellulitis/drained abscess, ≤7 days for undrained abscess) were safe
- 2021 SIS guidelines support shorter courses with increased data for complex abscesses 4

Clinical Pearl: Retrospective data shows average 2-week treatment in hospitalized patients, but failure rates (12%) were identical regardless of spectrum breadth 1 - suggesting we often overtreat both duration and spectrum.

MCQ #4 (Difficult): "A patient with uncomplicated cellulitis shows marked improvement at day 5. What is the evidence-based duration?"

Tests knowledge of the 5-day vs. 10-day equivalence data

Section 4: De-escalation Strategy (10 minutes)

Algorithmic approach to de-escalation:

Step 1: Reassess at 48-72 hours

Clinical improvement (decreased erythema, pain, fever)?
Culture data available?

Step 2: De-escalate based on:

If MRSA coverage was empiric but cultures negative: Switch to β-lactam monotherapy 1
If broad-spectrum (e.g., piperacillin-tazobactam, carbapenems) was started: Narrow to pathogen-specific therapy based on susceptibilities 1
If IV therapy: Consider oral switch when:
- Afebrile >24 hours
- Hemodynamically stable
- Able to tolerate oral intake
- Improving local signs

Step 3: Document rationale

Stewardship programs increasingly emphasize documentation of de-escalation decisions 5

Common Pitfall: Two-thirds of hospitalized SSTI patients receive very-broad-spectrum treatment unnecessarily 1 - resist the urge to cover "everything possible"

MCQ #5 (Difficult): "Day 3: Patient on vancomycin + piperacillin-tazobactam for cellulitis. Blood cultures show MSSA. Appropriate de-escalation?"

Tests understanding of narrowing spectrum based on culture data

Section 5: Antibiotic Resistance & Special Populations (8 minutes)

Neutropenic Patients - Different Rules Apply 1:

Initial episode fever/neutropenia:

Hospitalize with vancomycin + antipseudomonal agent (cefepime, carbapenem, or piperacillin-tazobactam)
Duration: 7-14 days for most bacterial SSTIs
Surgical drainage after marrow recovery

Persistent/recurrent fever (after 4-7 days):

Add empiric antifungal therapy (yeasts/molds are primary cause) 1
Add vancomycin/linezolid/daptomycin if not already given
Consider resistant organisms

Resistance Patterns - Regional Variation 6, 7:

Management complexity increases with regional MRSA prevalence
Know your local antibiogram
Rapid diagnostic tests increasingly useful for selection and de-escalation 6

MCQ #6 (Difficult): "Neutropenic patient with SSTI and persistent fever on day 6 of cefepime + vancomycin. Next step?"

Tests understanding of fungal coverage in persistent neutropenic fever

Section 6: Severe/Necrotizing SSTIs (7 minutes)

Recognize these require different management 6, 4:

Intensive care
Immediate surgical consultation for source control - this is non-negotiable
Broad-spectrum antimicrobials initially
Clinical prediction scores may help identify patients NOT requiring MRSA coverage 6

Necrotizing fasciitis/myonecrosis:

Surgical debridement is primary therapy
Antimicrobials are adjunctive
Progressive polymicrobial infections require aggressive intervention 1

Take-Home Messages (5 minutes)

The Five Commandments of SSTI Management:

"Pus requires drainage, not just drugs" - Distinguish purulent from non-purulent SSTIs; drainage is primary for abscesses 1
"MRSA coverage is the exception, not the rule" - β-lactam monotherapy succeeds in 96% of typical cellulitis; add MRSA coverage only for penetrating trauma, purulent drainage, or concurrent MRSA infection 1
"Five days is enough for uncomplicated cellulitis" - If improved by day 5, stop at 5 days rather than reflexively prescribing 10-14 days 1
"De-escalate at 48-72 hours" - Reassess and narrow spectrum based on clinical response and culture data; document your rationale 1, 5
"Surgical consultation cannot wait for necrotizing infections" - Source control is non-negotiable for severe SSTIs; antimicrobials alone will fail 6, 4

Resistance Stewardship Pearl:

Every unnecessary day of antibiotics and every unnecessarily broad spectrum contributes to resistance - the 2025 pediatric data showing safety of shorter courses 3 and the 2021 SIS guidelines supporting duration reduction 4 give us permission to treat less, not more.

Presentation Engagement Strategies

Based on the evidence that PowerPoint-heavy formats lead to poor retention 2:

Intersperse MCQs every 8-10 minutes (6 total as outlined above)
Use clinical images liberally (erysipelas vs. cellulitis, necrotizing fasciitis)
Case-based progression: Return to opening case throughout, showing how principles apply
Audience polling: "How many days would YOU prescribe?" before revealing evidence
Avoid text-heavy slides: Use algorithms, flowcharts, and tables instead
Reference the IDSA guidelines explicitly 1 as the textbook equivalent - encourage trainees to read them

The 2007 study 2 demonstrated that active learning with textbook integration (vs. PowerPoint + MCQs alone) dramatically improved performance - your presentation should drive trainees to the IDSA guidelines, not replace them.

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