Automated Allergy and Infectious Disease Pharmacy Consult to Limit the Use of Aztreonam in Patients with Reported Beta-Lactam Allergy

Rationale: True IgE mediated hypersensitivity and severe delayed reactions due to penicillin are relatively uncommon, even in patients with reported beta-lactam allergy. Inpatients with reported beta-lactam allergies frequently receive alternative antibiotics which are often less appropriate and more expensive than patients without a reported penicillin allergy.

Methods: The University of Washington Medical Center (UWMC) is a tertiary/quaternary care center with a significant number of inpatients with reported beta-lactam allergies. Given the high number of such patients admitted to UWMC, starting in June 2014 all inpatients prescribed IV aztreonam generated an automated alert; depending on the allergy history, either the Allergy/Immunology and/or Infectious Disease team on call reviewed the patient records and consulted after discussion with the primary inpatient service. This retrospective review evaluates all patients who received this intervention from June 2014 to June 2015.

Results: Of the 98 patients with aztreonam orders, 75 had documented beta-lactam allergies. Of these patients, 26 were successfully challenged to an alternative beta-lactam, 12 underwent skin testing and challenge, and 1 underwent desensitization. In total, 41/75 patients on aztreonam had therapy altered to a preferable therapy after evaluation. Additionally, 20/75 patients had penicillin allergy removed from their records after consultation and another 18/75 were amended to tolerate cephalosporins. No adverse events related to testing or challenges were reported. 

Conclusions: The use of an automated allergy/infectious disease consult was able to significantly impact the care of inpatients with reported beta-lactam allergies, reduce the use of aztreonam in the inpatient setting, and prevent unnecessary use of alternate antibiotics.