What is the treatment for guttate psoriasis potentially triggered by a streptococcal infection with an elevated Antistreptolysin O (ASO) titre?

Treatment of Guttate Psoriasis with Elevated ASO Titre

For guttate psoriasis potentially triggered by streptococcal infection with elevated ASO titre, topical corticosteroids combined with UVB phototherapy is the recommended first-line treatment, with consideration of antibiotic therapy despite limited evidence of efficacy.

First-Line Treatment Options

Topical Therapy

• High to moderate potency topical corticosteroids are the most rapid and efficient first-line treatment for mild guttate psoriasis 1
  • Apply once or twice daily for 2-4 weeks 2
  • For widespread lesions, consider combination with vitamin D analogs for enhanced efficacy 2
  • For sensitive areas (face, intertriginous areas), use low-potency corticosteroids or topical calcineurin inhibitors 2

Phototherapy

• Ultraviolet B (UVB) phototherapy is the first-line therapy for moderate-to-severe guttate psoriasis 1
  • More practical than topical therapy when treating widespread small lesions
  • Can be combined with topical treatments for enhanced efficacy

Role of Antibiotic Therapy

Despite the association between streptococcal infection and guttate psoriasis:

• Evidence for antibiotic efficacy is very limited and of low quality 3, 4
• A systematic review found no firm evidence supporting antibiotics in established guttate psoriasis 4
• However, one study suggested penicillin should be considered when streptococcal infection is confirmed 5

Antibiotic Considerations

• If antibiotic therapy is pursued:
  • Penicillin (50,000 IU/kg/day in three doses for 14 days) or
  • Erythromycin (250 mg four times daily for 14 days) for penicillin-allergic patients 3
  • Treatment duration typically 10-14 days

Treatment Algorithm

1. Assess disease severity:

   • Mild (<3% BSA): Topical therapy alone
   • Moderate-to-severe (>3% BSA): Consider phototherapy

2. For mild disease:

   • Start with high-potency topical corticosteroids once or twice daily
   • After 2-4 weeks, evaluate response
   • If improved, transition to maintenance with vitamin D analog or combination therapy

3. For moderate-to-severe disease:

   • Initiate UVB phototherapy
   • Consider combining with topical treatments
   • Evaluate response after 4 weeks 2

4. For confirmed streptococcal infection with elevated ASO:

   • Consider a course of appropriate antibiotics (penicillin or erythromycin)
   • Continue topical therapy and/or phototherapy concurrently

Important Caveats

• Spontaneous remission may occur within 3-4 months without treatment 1
• Risk of progression: 40-50% of guttate psoriasis cases may persist and progress to chronic plaque psoriasis 1
• Monitor for side effects:
  • Skin atrophy, telangiectasia with topical corticosteroids
  • Photosensitivity with UVB therapy
  • Gastrointestinal effects with antibiotics

Treatment-Resistant Cases

For cases not responding to first-line therapy:

• Consider systemic immunosuppressive therapies such as methotrexate or cyclosporine 1
• Biologics may be considered for severe, resistant cases 1
• Tonsillectomy has been suggested for recurrent streptococcal-triggered psoriasis, but evidence is limited 3