A Case of Vancomycin-Induced Drug Reaction with Eosinophilia, Systemic Symptoms and Multiorgan Involvement Proven Using Lymphocyte Transformation Test.

Drug-induced hypersensitivity syndrome (DiHS), also referred to as drug reaction with eosinophilia and systemic symptoms (DRESS), is a rare but potentially life-threatening condition induced by drug hypersensitivity that leads to significant morbidity and mortality and often occurs in patients undergoing combination antibiotic therapy. Due to a recent increase in the incidence of methicillin-resistant infections, the occurrence of vancomycin-induced DiHS/DRESS has increased rapidly. However, because of insufficient pharmacogenetic data on vancomycin-induced drug eruptions in Asians coupled with the risk of re-eliciting the symptoms by provocation tests, confirmation of the culprit drug in vancomycin-induced DiHS/DRESS is often challenging. Here, we report a case of vancomycin-induced DiHS/DRESS, where the causal relationship was confirmed using a lymphocyte transformation test (LTT). A 51-year-old woman was treated with combination antibiotics, including vancomycin, for infective pericarditis. The patient subsequently developed fever, facial edema, generalized rash followed by multiple internal organ involvement, including the kidney, lung, liver, and heart. Thus, based on the International Registry of Severe Cutaneous Adverse Reaction (RegiSCAR) criteria, the case was diagnosed as 'definite' DiHS/DRESS, although the culprit drug was obscured by combination antibiotic therapy. The LTT confirmed that vancomycin, but not other glycopeptide antibiotics, specifically induced T-cell proliferation in this case. Collectively, our case suggests that clinicians can utilize LTT to identify the causative medication of DiHS/DRESS when the clinical information is limited to defining the culprit drug.