Materials and Methods: Cross-sectional study of fifteen patients with an history of immediate hypersensitivity reactions to common BL drug group, at Ramathibodi Hospital between 2010 and 2012. All subjects underwent ST, and DPT if ST was negative. BAT was done in all patients.

Results: Fifteen patients (10 children and 5 adult), including seven male and eight female cases with history of highly indicated immediate type allergic reactions to beta lactam were examined. Five presented with anaphylaxis and 10 with urticarial rash/angioedema. From fifteen patients, eight patients were confirmed allergic to BL, where four had ST positivity, and four had positive DPT. The present study found one patient with severe anaphylaxis that had negative ST, but could not undergo DPT due to underlying diseases. The alternative test BAT yielded positive result. Four of the eight patients were confirmed as BL allergic patients with positive BAT (50%). None of the patients with negative drug testing had positive BAT. Estimated sensitivity of ST was similar to BAT at 50%, while specipicity of BAT in the present study was 100%. The result yielded higher sensitivity, such as 62%, when we combined both tests together (ST and BAT). The authors observed BAT positive results in 75% of patients with positive ST, and 25% of patients positive DPT.

Conclusion: BAT has an advantage in patients contraindicated to perform DPT. Moreover, BAT can avoid the risk of reproducible reactions from in vivo testing, especially in high-risk patients allergic to BL. BAT is a promising alternate investigation tool ensuring patients’ safety.

Keywords: BL hypersensitivity, Drug allergy, Drug hypersensitivity, Immediate type hypersensitivity, Drug allergy testing