What is the best treatment for a blister with a possible impetigo infection?

Treatment of Blisters with Suspected Impetigo Infection

For blisters with suspected impetigo infection, the recommended treatment is topical mupirocin 2% ointment applied three times daily for 7-10 days, which has shown 71-93% clinical efficacy rates in treating impetigo. 1, 2

Assessment and Diagnosis

• Examine the blister for signs of impetigo infection:
  • Honey-colored crusts (nonbullous impetigo)
  • Large, flaccid bullae (bullous impetigo)
  • Surrounding redness, warmth, increasing pain, or pus 2, 3

Treatment Algorithm

Step 1: Cleaning and Preparation

1. Gently cleanse the area with an antimicrobial solution 2
2. For intact blisters:
   • Pierce the blister at its base with a sterile needle
   • Apply gentle pressure with sterile gauze to facilitate drainage
   • Leave the blister roof intact to serve as a biological dressing 2

Step 2: Antimicrobial Treatment

For Limited Lesions:

• First-line: Mupirocin 2% ointment applied three times daily 1, 4
  • Clinical efficacy rates: 71-93%
  • Pathogen eradication rates: 94-100%
  • Duration: 7-10 days

For Extensive Infection or Treatment Failure:

• Oral antibiotic options: 4
  • Dicloxacillin: 250 mg 4 times per day (adults)
  • Cephalexin: 250 mg 4 times per day (adults)
  • Clindamycin: 300-400 mg 3 times per day (adults)
  • Amoxicillin/clavulanate: 875/125 mg twice per day (adults)

For Suspected MRSA:

• Consider the following options: 4
  • Clindamycin (if local resistance rates are low)
  • Trimethoprim-sulfamethoxazole
  • Doxycycline (not for children under 8 years)
  • Linezolid (for severe cases)

Step 3: Wound Care

• Apply a non-adherent dressing if necessary 2
• Daily washing with antibacterial products to decrease colonization 2
• For extensive areas, consider antiseptic baths or soaks 2

Special Considerations

Pediatric Patients

• Mupirocin is effective and safe for pediatric patients 1
• Tetracyclines should not be used in children under 8 years of age 4
• Adjust oral antibiotic dosing based on weight:
  • Dicloxacillin: 12 mg/kg/day in 4 divided doses
  • Cephalexin: 25 mg/kg/day in 4 divided doses 4

Pain Management

• Offer appropriate analgesia prior to beginning the procedure 2
• Consider over-the-counter pain relievers like acetaminophen or NSAIDs if needed 2

When to Seek Further Medical Attention

• If signs of worsening infection develop (increasing redness, warmth, pain, red streaks)
• If the blister is large (>30% body surface area) or involves mucous membranes
• If there is no improvement after 3-5 days of treatment 2, 3

Important Caveats

• Topical disinfectants are inferior to antibiotics and should not be used 5
• Be aware of increasing prevalence of antibiotic-resistant bacteria 3
• Oral penicillin V is seldom effective for impetigo treatment 5
• Erythromycin resistance rates are rising, making it a less reliable option 3

Mupirocin has excellent in vitro activity against staphylococci and streptococci, the predominant pathogens in impetigo, with fewer adverse effects than systemic antibiotics 6, 7. It works by inhibiting bacterial protein synthesis through a unique mechanism of action 8.