A new testing approach for vancomycin reactions

Published online August 5, 2024

Vancomycin is a commonly used antibiotic, especially important for treating serious infections. However, many patients experience side effects such as skin itching, flushing, and sometimes even difficulty breathing during infusions, including first-time infusions. These reactions, known as vancomycin infusion reactions, are often mistaken for true allergic reactions, leading to unnecessary restrictions on this essential antibiotic. Unlike true allergies, which are triggered by well-known allergy antibodies (IgE), most, if not all, vancomycin infusion reactions are caused by a recently discovered receptor on skin allergy cells called MRGPRX2, short for mas-related G protein-coupled receptor X2. However, the clinical similarities between these reactions and the lack of tests to identify those triggered by this newly identified receptor often lead to misclassification and unnecessary restrictions on vancomycin use, even when it may be critically needed.

In a recent study published in The Journal of Allergy and Clinical Immunology: In Practice, Alvarez-Arango et al. developed a skin test strategy to help distinguish vancomycin infusion reactions from true IgE-mediated vancomycin allergies. They tested two groups: one that had previously experienced infusion reactions to vancomycin and another that had tolerated it without issues. Each participant underwent skin tests at different vancomycin doses to create a “dose-response” curve, measuring their sensitivity to the drug. The study also examined a blood test called the basophil activation test to determine if it could help identify vancomycin infusion reactions.

The study found that patients with a history of vancomycin infusion reactions responded to much lower doses of vancomycin in skin testing compared to those who tolerated the drug without issues, with a skin dose response approximately 3.5 times lower. Additionally, all patients with infusion reactions reported skin symptoms, such as localized itching, during the skin test, while only some individuals in the tolerant group experienced similar symptoms. The basophil activation test showed no response to vancomycin stimulation, supporting the involvement of MRGPRX2. However, the skin testing protocol demonstrated potential as a tool to identify these reactions and could become a practical diagnostic approach for risk assessment in clinical settings. With further research, this skin testing method could be validated across a broader patient population, ultimately establishing it as a standard for assessing sensitivity to vancomycin and potentially other drugs that activate MRGPRX2.

The Journal of Allergy and Clinical Immunology: In Practice is an official AAAAI journal focusing on practical information for the practicing clinician.

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