What is the recommended treatment for a patient with a skin infection who is allergic to penicillin (antibiotic)?

Treatment of Skin Infections in Patients with Penicillin Allergy

For patients with skin infections who are allergic to penicillin, the recommended first-line treatment options are clindamycin, trimethoprim-sulfamethoxazole (TMP-SMX), or doxycycline, depending on the suspected pathogen and severity of infection. 1, 2

First-Line Treatment Options

• Clindamycin (300-450 mg orally four times daily) is effective for both methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) infections 1, 2
• Trimethoprim-sulfamethoxazole (1-2 double-strength tablets twice daily) is particularly effective for suspected MRSA infections but should not be used as monotherapy for cellulitis without a drainable abscess due to possible group A Streptococcus resistance 1, 2
• Doxycycline (100 mg orally twice daily for 7-10 days) can be safely used in patients ≥2 years old and is effective against both MSSA and MRSA 1, 3

Treatment Based on Infection Severity

For Non-Severe Infections:

• Incision and drainage is the cornerstone of treatment for skin abscesses, regardless of antibiotic use 1
• Culture of the wound should be obtained during drainage to identify the causative agent and determine antimicrobial susceptibility 1
• Standard duration of antibiotic therapy is 7-10 days for uncomplicated infections 1, 2

For Severe Infections:

• Vancomycin is the drug of choice for severe infections in penicillin-allergic patients, especially for MRSA coverage 2
• Clindamycin can be used intravenously (600 mg every 8 hours) for both MSSA and MRSA when parenteral therapy is needed 2
• Antibiotics are strongly recommended in patients with systemic inflammatory response syndrome (SIRS) 1

Antibiotic Selection Based on Allergy Type

• For patients with severe/immediate penicillin hypersensitivity (urticaria, angioedema, bronchospasm, or anaphylaxis), avoid all beta-lactam antibiotics including cephalosporins 2, 4
• For patients with non-immediate or unclear penicillin allergy history, consider allergy assessment and penicillin skin testing when appropriate 2, 4
• Properly performed skin testing using major and minor penicillin determinant reagents has a negative predictive value of 97%-99% 2, 4

Special Considerations

• If MRSA is suspected or prevalent in your area, TMP-SMX or doxycycline should be preferred 1, 5
• For mixed aerobic/anaerobic infections, consider clindamycin with either a fluoroquinolone or metronidazole 2
• Patients with recurrent abscesses should be considered for decolonization regimens including intranasal mupirocin and chlorhexidine washes 1

Pitfalls and Caveats

• TMP-SMX should not be used as monotherapy for cellulitis without a drainable abscess, as it may not cover group A Streptococcus 1
• With the global emergence and spread of macrolide-resistant S. aureus and beta-hemolytic streptococci, clindamycin rather than a macrolide is the recommended agent for empirical antibacterial therapy of community-acquired skin infections in penicillin-allergic patients 6
• Patients labeled as having a penicillin allergy are exposed to more alternative antibiotics and have increased prevalence of C. difficile, MRSA, and vancomycin-resistant enterococcal infections 2, 4
• Only approximately 10% of persons who report a history of severe allergic reactions to penicillin are still allergic after 10 years 4, 7