Beta-Lactam Allergy Testing at the Bedside

Concern about allergy to penicillin and other beta-lactam antibiotics has led to increased, and sometimes inappropriate, use of broader-spectrum and more-expensive drugs. Studies have shown that most individuals with histories of “penicillin allergy” rarely have allergic attacks when challenged with beta-lactams. However, fear of the consequences of such an attack on medical and legal grounds have diminished use of beta-lactams and increased use of less-efficacious agents.

This multicenter, prospective study was conducted to see whether point-of-care beta-lactam allergy skin testing (BLAST) carried out as part of an antibiotic stewardship program (ASP) would allow greater use of beta-lactams, thereby providing, in some cases, better antibiotic coverage and resulting in lower cost and exposure to fewer broad-spectrum antibiotics, with no increase in adverse outcomes. After a baseline period to establish practice norms in three hospitals in Toronto, Canada, teams consisting of an infectious disease specialist and pharmacists trained in BLAST and emergency allergy care administered BLAST to 827 infected patients with histories of beta-lactam allergy. In 76% of these patients, a beta-lactam was deemed preferred therapy. The labor-intensive testing required an hour per intervention. Patients with histories of severe reactions such as anaphylaxis or urticaria were excluded.

During baseline, 50% of patients received beta-lactams based on history. This proportion increased to 60% with ASP intervention but no BLAST and to 81% when BLAST was used. The odds of infected patients receiving preferred beta-lactam therapy was increased 4.5-fold during the intervention period versus baseline. Adverse drug-related events did not increase.