Treatment of Ecthyma
For ecthyma, obtain cultures and initiate oral antibiotics for 7 days: use dicloxacillin or cephalexin for presumed MSSA, or switch to doxycycline, clindamycin, or sulfamethoxazole-trimethoprim when MRSA is suspected or confirmed. 1
Diagnostic Approach Before Treatment
- Always obtain cultures from vesicle fluid, pus, erosions, or ulcers to establish the causative organism before initiating therapy 1
- Gram stain and culture of pus guide targeted antibiotic selection 1
- This step is critical because ecthyma can be caused by different organisms requiring different antibiotics
Empiric Antibiotic Selection Algorithm
For Presumed MSSA (Methicillin-Susceptible S. aureus)
- Dicloxacillin OR cephalexin for 7 days are the first-line choices 1
- These agents provide excellent coverage against the most common causative organism in ecthyma
When MRSA is Suspected or Confirmed
- Switch to doxycycline, clindamycin, or sulfamethoxazole-trimethoprim (SMX-TMP) 1
- In areas with high MRSA prevalence, empiric therapy should cover MRSA until culture results return 1
- This is a critical consideration in many geographic regions where community-acquired MRSA is endemic
For Streptococci Alone (Culture-Confirmed)
- Penicillin is the drug of choice when cultures confirm streptococci without staphylococcal co-infection 1
- For penicillin-allergic patients, use a macrolide or clindamycin 1
Treatment Duration
- Continue oral antibiotic therapy for 7 days as the standard duration 1
- Some sources suggest 7-14 days for bacterial skin and soft tissue infections, but 7 days is the recommended minimum 1
Special Clinical Situations
During Outbreaks of Poststreptococcal Glomerulonephritis
- Use systemic antimicrobials to eliminate nephritogenic strains of S. pyogenes 1
- This prevents serious renal complications in outbreak settings
Important Caveat: Ecthyma Gangrenosum
- While the question asks about ecthyma (a deeper form of impetigo), be aware that ecthyma gangrenosum is a distinct, life-threatening condition requiring different management 2, 3, 4
- Ecthyma gangrenosum presents with rapidly progressive necrotic lesions with black eschars, typically from Pseudomonas aeruginosa sepsis, and requires immediate antipseudomonal antibiotics and intensive care 3, 4, 5
- This is a critical pitfall: if you see rapidly evolving necrotic lesions with surrounding erythema and systemic symptoms (fever, sepsis), this is NOT simple ecthyma and requires urgent escalation of care 4, 5