What alternative antibiotics can be used in patients with a penicillin allergy?

From the Guidelines

For patients with a penicillin allergy, the most appropriate alternative antibiotics to use are those that minimize the risk of cross-reactivity and are effective against the specific infection being treated, such as macrolides, fluoroquinolones, tetracyclines, or vancomycin, as recommended by the most recent guideline 1. When considering alternative antibiotics for patients with penicillin allergies, it's essential to assess the severity and type of allergic reaction, as well as the specific infection being treated.

• Macrolides like azithromycin (500mg daily for 3-5 days) and clarithromycin (250-500mg twice daily for 7-14 days) are common alternatives for respiratory infections.
• Fluoroquinolones including levofloxacin (500-750mg daily) and ciprofloxacin (250-750mg twice daily) are effective for various infections but should be used judiciously due to side effect concerns.
• Tetracyclines like doxycycline (100mg twice daily) work well for respiratory, skin, and some sexually transmitted infections.
• For serious infections, vancomycin (15-20mg/kg IV every 8-12 hours) or linezolid (600mg twice daily) may be necessary, as suggested by previous guidelines 1. The choice of alternative antibiotic should be based on the specific infection, local resistance patterns, patient factors, and the severity of the previous allergic reaction, as emphasized in the latest guideline 1. It's also crucial to clarify the nature of the penicillin allergy, as many patients reporting allergies can actually tolerate penicillins or related antibiotics, and to consider the potential for cross-reactivity with other antibiotics, such as cephalosporins, which may be used in patients with non-severe penicillin allergies, though with caution due to the approximately 10% cross-reactivity rate 1.

From the FDA Drug Label

Vancomycin Hydrochloride for Injection, USP is indicated for the treatment of serious or severe infections caused by susceptible strains of methicillin-resistant (β-lactam-resistant) staphylococci It is indicated for penicillin-allergic patients, for patients who cannot receive or who have failed to respond to other drugs, including the penicillins or cephalosporins, and for infections caused by vancomycin-susceptible organisms that are resistant to other antimicrobial drugs

Alternative antibiotics for penicillin-allergic patients include:

• Vancomycin, as it is specifically indicated for penicillin-allergic patients 2 Key considerations:
• Vancomycin is effective against methicillin-resistant staphylococci and vancomycin-susceptible organisms
• It should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria

From the Research

Alternative Antibiotics for Patients with Penicillin Allergy

In patients with a penicillin allergy, alternative antibiotics can be used. The choice of antibiotic depends on the type of infection and the severity of the allergy.

• Cephalosporins: These antibiotics have a low cross-reactivity with penicillin, with a rate of approximately 1% to 2% 3, 4, 5. First-generation cephalosporins have a higher cross-reactivity than second-generation cephalosporins 5.
• Macrolides: These antibiotics, such as azithromycin and amoxicillin, can be used as an alternative to penicillin 6.
• Carbacephem: This antibiotic has been shown to be effective in treating group A streptococcal pharyngitis, with low-certainty evidence suggesting it may be more effective than penicillin in symptom resolution 6.
• Clindamycin: This antibiotic can be used as an alternative to penicillin, but it has a higher risk of adverse events, such as Clostridium difficile infection 7.

Assessment of Penicillin Allergy

Before using alternative antibiotics, it is essential to assess the patient's penicillin allergy. This can be done through:

• Penicillin skin testing: This test can help identify patients with a true penicillin allergy, with a negative predictive value of over 95% 3.
• Medical history: Patients with a low-risk history of penicillin allergy, such as isolated non-allergic symptoms or a family history of penicillin allergy, may be suitable for an oral rechallenge with low-dose penicillin 4.
• Direct amoxicillin challenge: This test can be used for patients with a low-risk allergy history, and can help identify patients who are no longer allergic to penicillin 3.

Important Considerations

When using alternative antibiotics in patients with a penicillin allergy, it is essential to consider the following:

• Cross-reactivity: While the cross-reactivity between penicillin and cephalosporins is low, it is still possible for patients to experience an allergic reaction 5.
• Adverse events: Alternative antibiotics, such as clindamycin, may have a higher risk of adverse events, such as Clostridium difficile infection 7.
• Antimicrobial stewardship: The use of broad-spectrum antibiotics can contribute to antimicrobial resistance, and alternative antibiotics should be chosen carefully to minimize this risk 3, 7.