What is the best treatment for a patient with infected eczema who is allergic to flucloxacillin (Flucloxacillin) and cephalexin (Cephalexin)?

Treatment for Infected Eczema in Patients Allergic to Flucloxacillin and Cephalexin

For patients with infected eczema who are allergic to both flucloxacillin and cephalexin, erythromycin is the recommended antibiotic treatment of choice. 1

First-Line Treatment Approach

Antibiotic Selection

• Erythromycin is the appropriate first-line antibiotic for patients with penicillin allergy (including flucloxacillin) and cephalosporin allergy 1
• Standard adult dosing: 250-500 mg four times daily for 7-10 days
• Pediatric dosing should be adjusted according to weight

Alternative Options

If erythromycin cannot be tolerated due to gastrointestinal side effects (which are common):

1. Clindamycin is a reasonable alternative with only 1% resistance among Staphylococcus aureus isolates in the US 1, 2

   • Adult dosing: 300-450 mg three times daily
   • Pediatric dosing: 10-30 mg/kg/day divided in 3-4 doses

2. Clarithromycin can be considered as it has fewer gastrointestinal side effects than erythromycin 3

   • Adult dosing: 250 mg twice daily
   • Treatment duration: 7-14 days

3. Azithromycin may be used for a shorter course of therapy 1, 4

   • Adult dosing: 500 mg on day 1, followed by 250 mg daily on days 2-5
   • Advantage: Better compliance with once-daily dosing and shorter course

Comprehensive Management

Non-Antibiotic Measures (Equally Important)

1. Topical corticosteroids - Continue or initiate appropriate potency based on severity

   • Use the least potent preparation required to control eczema 1
   • Apply no more than twice daily

2. Emollients - Essential for skin barrier repair

   • Apply liberally and frequently, especially after bathing 1
   • Most effective when applied to damp skin

3. Bathing

   • Use suitable bath oils as recommended by dermatologist
   • Avoid soaps and detergents which remove natural skin lipids 1

4. Avoidance of triggers

   • Keep nails short to minimize damage from scratching
   • Wear cotton clothing rather than wool or synthetic fabrics 1
   • Avoid extremes of temperature

5. Sedating antihistamines may be useful for short-term management of pruritus 1

   • Non-sedating antihistamines have little value in atopic eczema

Important Considerations and Caveats

When to Consider Referral

• Failure to respond to first-line management 1
• Severe or widespread infection
• Recurrent infections requiring frequent antibiotic courses
• Signs of systemic illness

Cautions with Macrolide Antibiotics

• Macrolides (erythromycin and clarithromycin) can cause QT interval prolongation 1
• Avoid concurrent use with medications that inhibit cytochrome P-450 3A (azole antifungals, HIV protease inhibitors, some selective serotonin reuptake inhibitors) 1
• Monitor for gastrointestinal side effects, particularly with erythromycin

Evidence on Antibiotics for Infected Eczema

Recent research suggests caution in overusing antibiotics for clinically infected eczema that is not severe. A 2017 study found that in children with mild clinically infected eczema, antibiotics (both oral and topical) provided no additional benefit over standard treatment with emollients and topical corticosteroids 5. However, this applies primarily to mild infections, and patients with signs of more severe infection were excluded from these studies.

Antimicrobials to Avoid

• Tetracyclines (high prevalence of resistant strains) 1
• Sulfonamides and trimethoprim-sulfamethoxazole (ineffective against S. aureus in this context) 1
• Fluoroquinolones (unnecessarily broad spectrum and expensive) 1

By following this treatment approach, most patients with infected eczema who have allergies to flucloxacillin and cephalexin should respond well to appropriate antibiotic therapy combined with good eczema management.