What is the best treatment for a pustule?

Treatment of Pustules

For isolated pustules consistent with impetigo, apply topical mupirocin ointment three times daily to the affected area, which is as effective as oral antibiotics and is the preferred first-line treatment. 1, 2

Initial Assessment and Culture Guidance

• Obtain cultures of pustule fluid or pus to establish the causative organism, particularly for carbuncles, abscesses, and when systemic symptoms are present 1
• Do not routinely culture inflamed epidermoid cysts, as inflammation typically results from cyst wall rupture rather than infection 1
• Gram stain can provide rapid preliminary guidance for antibiotic selection 1

Treatment Based on Clinical Presentation

Impetigo (Superficial Pustules with Crusting)

Topical therapy is preferred for localized disease:

• Apply mupirocin ointment 2% to affected areas three times daily for 8-12 days, covering with gauze dressing if desired 2
• Mupirocin demonstrates 71% clinical efficacy versus 35% for placebo, with 94% pathogen eradication rates 2
• Retapamulin is an alternative topical agent with comparable efficacy 1
• Re-evaluate patients who fail to respond within 3-5 days 2

Systemic therapy is indicated when:

• Multiple lesions are present 1
• Outbreaks affect several people (to decrease transmission) 1
• Topical therapy fails 1

For systemic treatment:

• Prescribe oral penicillinase-resistant penicillin (such as dicloxacillin) or first-generation cephalosporins (such as cephalexin) for 7-10 days as first-line agents, since most staphylococcal isolates from impetigo are methicillin-susceptible 1, 3
• For penicillin-allergic patients or confirmed MRSA, use doxycycline, clindamycin, or trimethoprim-sulfamethoxazole (TMP-SMX) based on local resistance patterns 1, 3
• When streptococci alone are isolated, penicillin is the drug of choice, with macrolides or clindamycin as alternatives for penicillin-allergic patients 1

Furuncles and Carbuncles (Deep Follicular Pustules)

Incision and drainage is the primary treatment:

• Perform incision and drainage for all large furuncles and carbuncles, with thorough evacuation of pus and probing to break up loculations 1
• Simply cover the surgical site with a dry dressing rather than packing with gauze, as one study found packing causes more pain without improving healing 1
• Small furuncles may be managed with moist heat alone to promote spontaneous drainage 1

Adjunctive antibiotics are indicated only when:

• Systemic inflammatory response syndrome (SIRS) is present (temperature >38°C or <36°C, tachypnea >24 breaths/minute, tachycardia >90 beats/minute, or WBC >12,000 or <4,000 cells/µL) 1
• Extensive surrounding cellulitis develops 1
• Multiple lesions are present 1
• The patient has markedly impaired host defenses 1

When antibiotics are needed, prescribe an agent active against MRSA given the prevalence of community-acquired MRSA in skin abscesses 1

Cutaneous Abscesses

• Incision and drainage alone is sufficient treatment for most cutaneous abscesses 1
• Gram stain, culture, and systemic antibiotics are rarely necessary unless SIRS, multiple lesions, extensive cellulitis, or severely impaired immunity are present 1
• Do not attempt ultrasonographically-guided needle aspiration, as a randomized trial showed only 25% success overall and <10% success with MRSA infections 1

Hidradenitis Suppurativa (Chronic Pustules in Axillae/Groin)

For initial presentation:

• Start oral doxycycline 100 mg daily or lymecycline 300-600 mg daily for at least 12 weeks as first-line systemic therapy 4
• Always combine with topical benzoyl peroxide to prevent antimicrobial resistance 4
• Do not use topical antibiotics as monotherapy, as this is ineffective and promotes resistance 4

For tetracycline-refractory cases after 12 weeks:

• Escalate to combination therapy with oral clindamycin 300 mg twice daily PLUS rifampicin 300 mg twice daily for 10-12 weeks 4

Common Pitfalls to Avoid

• Do not use systemic antibiotics routinely for simple abscesses after adequate incision and drainage, as drainage alone is curative in most cases 1
• Do not pack abscess cavities with gauze, as this increases pain without improving outcomes 1
• Do not prescribe systemic corticosteroids for pustular psoriasis, as they risk severe flares upon discontinuation and can trigger erythrodermic transformation 5
• Avoid isotretinoin for hidradenitis suppurativa unless concomitant moderate-to-severe acne is present elsewhere 4

Special Considerations

For recurrent abscesses:

• Search for local causes such as pilonidal cysts, hidradenitis suppurativa, or foreign material 1
• Consider decolonization strategies including chlorhexidine bathing and thorough laundering of clothing and linens for outbreak settings 1

For pustular psoriasis with fever and extensive body surface involvement:

• Administer infliximab 5 mg/kg for rapid control of severe generalized pustular psoriasis 5
• Acitretin 0.1-1 mg/kg/day is effective for pustular variants but requires mandatory contraception counseling 1, 5

For neutropenic patients with fever and pustules:

• Immediately hospitalize and initiate empiric vancomycin plus antipseudomonal antibiotics (cefepime or piperacillin-tazobactam) before culture results, as delaying treatment increases mortality from gram-negative sepsis 5