Published online: March 27, 2019
Penicillin (PCN) allergy is the most commonly reported drug allergy, with up to 10% of those in the community and 20% of hospitalized patients self-reporting allergic reactions. However, following penicillin skin testing (PST), only 10% of those who self-report allergies are found to have a true immunoglobulin (Ig) E–mediated reaction. Use of PST to confirm PCN allergies is safe and effective in immunocompetent patients, however, there was a scarcity of data in immunocompromised patients.
In an article recently published in The Journal of Allergy and Clinical Immunology: In Practice, Taremi et al. report their findings after implementation of a PST program at MD Anderson Cancer Center, focusing on patients with leukemia and genitourinary cancers. Between April and October 2017, 218 hospitalized patients with reported PCN allergies were screened; 100 met inclusion criteria and underwent PST (67 leukemia, 33 genitourinary medical oncology). Patients underwent a two-part skin test followed by an oral challenge with amoxicillin.
The majority of patients (95%) tested negative on PST with oral challenge; only 4% of patients tested positive, and 1 test result was indeterminate due to a negative histamine control. Of tested patients, 67 (71%) had been receiving antibiotics prior to PST, and 50 of these patients (75%) were receiving non-PCN beta-lactam therapy (aztreonam, carbapenems, cephalosporins). Eleven patients had antibiotics discontinued the day of PST testing. Of the 39 patients that continued antibiotics, 20 (51%) were changed to PCN-based antibiotics (PBA) immediately following a negative PST and oral challenge. During the follow-up period (median 177 days), 65 of 95 patients were readmitted (185 total readmissions), 51 patients required antibiotic therapy, with 37 receiving a PBA (accounting for 336 days of therapy). No patient who received PCN-based antibiotics experienced a type I allergic reaction.
This study highlights that PST in immunocompromised patients is safe and effective in ruling out IgE-mediated penicillin allergy. Moreover, use of PST in cancer patients resulted in increased use of more narrow-spectrum, targeted therapies. Immunocompromised cancer patients are at increased risk for infections, and documented allergies are associated with worse outcomes including increased mortality. Implementation of PST at cancer centers is vital to improve clinical management and enhance antimicrobial stewardship in this population.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.