What is the medical term for an infected bug bite?

Medical Term for an Infected Bug Bite

The medical term for an infected bug bite is cellulitis, which is a bacterial infection of the skin and subcutaneous tissues that can develop when bacteria enter through a break in the skin caused by an insect bite. 1

Pathophysiology and Causative Organisms

Insect bites that become infected typically follow this progression:

• Initial minor skin trauma from the bite
• Introduction of bacteria through the compromised skin barrier
• Bacterial proliferation in the skin and soft tissues

Common causative organisms include:

• Staphylococcus aureus (most common)
• Streptococcus species (especially Group A streptococci)
• Less commonly, environmental organisms depending on exposure circumstances 1

Clinical Presentation

An infected bug bite will typically present with:

• Progressive erythema (redness) extending beyond the original bite site
• Swelling and induration
• Warmth
• Pain or tenderness
• Possible purulent drainage
• Systemic symptoms in severe cases (fever, malaise)

The key distinguishing feature between a simple inflammatory reaction to a bite and an infection is the progression of symptoms over time rather than improvement 1.

Diagnostic Approach

The diagnosis is primarily clinical, based on:

• History of insect bite
• Characteristic appearance of spreading erythema
• Signs of infection (progressive symptoms, purulence)

In complicated cases, consider:

• Culture of any purulent drainage to identify causative organisms
• Blood cultures if systemic symptoms are present 1

Treatment

Treatment should be initiated promptly to prevent progression:

1. Antimicrobial therapy:

   • For mild infections: Oral antibiotics covering Staphylococcus and Streptococcus

     • First-line: Amoxicillin-clavulanate (875/125 mg twice daily) 2
     • Alternatives for penicillin-allergic patients: Doxycycline, trimethoprim-sulfamethoxazole, or clindamycin 2

   • For severe infections: Intravenous antibiotics and possible hospitalization

2. Wound care:

   • Clean the area with mild soap and water
   • Apply warm compresses to improve circulation
   • Elevate the affected area if possible to reduce swelling

3. Incision and drainage:

   • If abscess formation is present, incision and drainage may be necessary 3

Special Considerations

• Unusual exposures: Consider special pathogens based on exposure history:

  • Animal contact: Consider Pasteurella species (especially from cat or dog bites) 2
  • Freshwater exposure: Consider Aeromonas hydrophila
  • Saltwater exposure: Consider Vibrio species 1

• Immunocompromised patients: Require more aggressive treatment and broader antimicrobial coverage due to risk of rapid progression 3

• Warning signs requiring urgent medical attention:

  • Rapid spread of erythema
  • Development of bullae or skin necrosis
  • Systemic symptoms (high fever, hypotension)
  • Wooden-hard feel of tissues (possible necrotizing infection) 1

Duration of Treatment

• Uncomplicated infections: 5-7 days of antibiotics
• Severe infections or immunocompromised hosts: 10-14 days 2

Most patients should show clinical improvement within 48-72 hours of appropriate antibiotic therapy. If no improvement is seen, reevaluation of diagnosis and antibiotic therapy is warranted 2.