Things We Do For No Reason: Failing to Question a Penicillin Allergy History

• Obtain a thorough drug allergy history as many “allergic reactions” can be removed by history alone. Update the medical record if you can confirm a patient has since tolerated PCN or a PCN derivative to which they were previously allergic. Offer a supervised oral challenge if the patient has any concerns.
• Perform PST if a patient has a PCN allergy listed in their chart and the allergy history is unclear. A negative skin test should be followed by a supervised oral challenge to PCN/PCN derivative if skin testing is negative.
• Test PCN-allergic patients preemptively who are at high risk of requiring PCN/PCN derivative antibiotics. High-risk patients include surgery, transplant, hematology/oncology, and immunosuppressed patients.
• Implement published protocols from allergists for healthcare systems that lack access to allergy physicians.
• Do not perform PST on patients with a history that is suggestive of a non-IgE-mediated allergic reaction. For these cases, patients are advised to avoid the medication. A supervised graded oral challenge can be considered on a case by case basis if the reaction was not a severe cutaneous adverse reaction syndrome, like SJS, and the benefit of using the medication outweighs the potential harm.

CONCLUSION

The patient, in this case, reported an allergic reaction to PCN over 50 years before this presentation. The reported reaction immediately after receiving IV PCN was a rash—a symptom concerning for an IgE-mediated reaction. Since the patient is well over 10 years from his allergic reaction and would benefit from a PCN derivative, PST testing should be pursued.

The patient passed his skin testing and an oral challenge dose of amoxicillin. With the PCN allergy removed from his chart, his medical team transitioned him from aztreonam and vancomycin to ampicillin. He was then discharged home on amoxicillin and informed that he might be safely treated with PCN/PCN derivatives in the future.

Given the rise in antimicrobial resistance and both the clinical implications and increased costs associated with PCN allergy, it is crucial to offer an allergy evaluation to patients identified as PCN allergic. Hospitalists play a crucial role in obtaining the initial history, determining if the patient has tolerated the antibiotic since the initial reaction, and identifying patients who may benefit from further evaluation for PCN allergy. In hospitals with PST available for inpatients, testing can be performed during the admission. Additionally, it is essential that allergists work with hospitalists and primary care physicians to provide seamless access to outpatient drug allergy evaluations (PST followed by oral challenge) to address the issue of PCN allergy before an acute need for a PCN/PCN derivative antibiotic in the hospital.

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