I have an acutely erythematous, swollen, painful finger without any known trauma; how should I manage it?

Management of Acute Erythematous, Swollen, Painful Finger Without Trauma

You should immediately assess for signs of serious infection requiring urgent surgical consultation, then initiate empiric antibiotics covering both Staphylococcus aureus (including community-acquired MRSA) and Streptococcus pyogenes while considering specific diagnoses based on clinical presentation. 1, 2

Immediate Assessment for Limb-Threatening Infection

First, examine for any of these urgent surgical indicators 1:

• Rapid progression of infection over hours
• Pain out of proportion to clinical findings (suggests necrotizing infection or deep space abscess)
• Crepitus on examination (indicates gas-forming organisms)
• New onset numbness in the finger (suggests compartment syndrome or nerve involvement)
• Extensive ecchymoses, petechiae, or hemorrhagic bullae
• Systemic signs: fever, tachycardia, hypotension, altered mental status

If any of these are present, obtain urgent surgical consultation immediately—do not delay for imaging. 1, 3

Differentiate Superficial vs. Deep Infection

Superficial Infections (Skin/Subcutaneous)

Examine for 3, 4:

• Paronychia: Erythema and swelling localized to the nail fold, often with visible pus collection
• Felon: Tense, throbbing pain in the fingertip pulp with inability to palpate the normal soft tissue give
• Cellulitis: Spreading erythema without clear borders, warm to touch, no fluctuance

Deep Infections (Require Urgent Surgical Referral)

Look specifically for 3, 4:

• Pyogenic flexor tenosynovitis: Check for Kanavel's four cardinal signs:
  • Fusiform swelling of entire finger
  • Finger held in slight flexion
  • Tenderness along flexor tendon sheath (not just at one point)
  • Pain with passive extension of the finger
• Septic arthritis: Swelling localized to a joint, severely painful range of motion 5
• Deep space abscess: Dorsal hand swelling with palmar wound suggests infection tracking through fascial planes 1

If any signs of deep infection are present, obtain immediate surgical consultation and do not delay for antibiotics or imaging. 3, 4

Consider Non-Bacterial Causes

Before initiating antibiotics, examine for 6, 4:

• Herpetic whitlow: Multiple grouped vesicles on an erythematous base, severe pain, history of oral herpes or healthcare work

  • Do NOT incise and drain—this worsens the condition 6, 4
  • Confirm with PCR testing if available 6
  • Treat with oral acyclovir or valacyclovir if within 48 hours of symptom onset 4

• Erysipeloid: Occupational exposure to fish, marine animals, swine, or poultry within past 7 days 1

  • Violaceous color with central clearing and target-like appearance 1
  • Treat with penicillin 500 mg four times daily or amoxicillin 500 mg three times daily for 7-10 days 1
  • Note: Erysipelothrix is resistant to vancomycin and daptomycin 1

Empiric Antibiotic Selection for Bacterial Infection

For Superficial Infections Without Abscess

Start oral antibiotics covering community-acquired MRSA and Streptococcus 2, 3:

• First choice: Trimethoprim-sulfamethoxazole DS twice daily PLUS cephalexin 500 mg four times daily 2
• Alternative: Doxycycline 100 mg twice daily (covers both MRSA and streptococci) 2
• If penicillin allergy: Clindamycin 300-450 mg three times daily 7, 2

For Abscess Present

Incision and drainage is the primary treatment 3, 4:

• Perform under digital block anesthesia
• Make adequate incision for complete drainage
• Break up loculations with hemostat
• Pack lightly if needed
• Add oral antibiotics as above if surrounding cellulitis, immunocompromised, or systemic symptoms 3

For Severe Infection or Failed Outpatient Management

Admit for IV antibiotics 2, 3:

• Vancomycin 15-20 mg/kg IV every 8-12 hours (target trough 15-20 mcg/mL for serious infections) 2
• Alternative: Daptomycin 4-6 mg/kg IV daily 2
• Add coverage for Streptococcus if vancomycin used alone: Consider adding ceftriaxone 1-2 g IV daily 2

Adjunctive Measures (Critical for All Cases)

Regardless of antibiotic choice 7, 3, 4:

• Strict elevation above heart level continuously for first 48 hours
• Splint in position of function (wrist 20° extension, MCP joints 70° flexion, IP joints 10° flexion)
• Warm soaks 3-4 times daily for 15-20 minutes once abscess drained or for early cellulitis
• Update tetanus if last dose >5 years ago and any break in skin 4

Follow-Up Timing

• Recheck in 24-48 hours for all superficial infections 3, 4
• Return immediately if: Worsening redness, increasing pain, fever, red streaking up arm, numbness develops 3
• If no improvement in 48 hours: Consider resistant organism, deeper infection, or alternative diagnosis—obtain surgical consultation 3, 4

Common Pitfalls to Avoid

• Do not assume all finger infections are bacterial—herpetic whitlow mimics bacterial infection but requires antiviral therapy, not incision 6, 4
• Do not miss flexor tenosynovitis—this requires urgent surgical irrigation within 24 hours to prevent permanent tendon damage and finger stiffness 3, 4
• Do not use vancomycin alone for empiric therapy—it does not adequately cover Streptococcus pyogenes, which causes rapidly progressive cellulitis 2
• Do not delay surgical consultation for imaging—clinical examination is sufficient to identify deep infections requiring urgent surgery 1, 3
• Do not forget to ask about occupational exposures—fish/meat handlers may have erysipeloid requiring penicillin, not typical MRSA coverage 1