While penicillin allergy testing is an emerging topic for 2017, healthcare providers are finding that new—and unexpected—patient populations do not understand the importance of penicillin allergy testing.
Penicillin allergies, reported in 10 percent of the population, are the most commonly documented drug allergy in the U.S. Yet nine out of 10 patients reporting a penicillin allergy are not actually allergic. i
Such patient chart mislabeling has led to the misuse and overuse of many broad-spectrum antibiotics, which often are more expensive than penicillin and associated with increased side effects. Additionally, and perhaps most importantly, the use of broad spectrum antibiotics has increased the risk of antibiotic resistance.
According to the Centers for Disease Control and Prevention (CDC), two million illnesses annually are caused by drug resistant bacteria and necessitate more complex care—such as prolonged and/or costlier treatments and extended hospital stays. At least 23,000 people die as a result of these drug-resistant infections each year. In addition, while difficult to accurately estimate, the direct costs of antibiotic resistance may be as high as $20 billion. As such, antibiotic resistance is a growing clinical and public health issue.ii
Five key points about penicillin allergy and testing
As we consider this rising trend, there are five key points providers and patients should know about penicillin allergies and penicillin allergy testing:
1. How is a penicillin allergy identified?
Penicillin allergies include IgE-mediated reactions to penicillin's reactive intermediates, called antigen determinants. Skin testing with the major and minor determinants of penicillin can reliably identify people at high risk for IgE-mediated reactions. Less than one percent of the patient population has a true immunoglobulin E (IgE)–mediated allergy to penicillin.
2. A significant number of people are not truly allergic.
About 90 percent of people labeled as allergic to penicillin are actually not allergic, which means penicillin allergy is probably over-diagnosed.
3. Penicillin allergy has no predictable inheritance pattern.
A family history of penicillin allergy has no relation to the likelihood of penicillin allergy for a given person. As a result, patients do not need to avoid penicillin simply because a family member has a documented penicillin allergy.iii
4. Penicillin allergy is lost over time.
Penicillin sensitivity can wane after approximately 10 years. This is even seen in patients who have experienced a severe reaction.
5. Skin testing is the most reliable way to determine if patients are penicillin allergic.
A skin testing protocol is recommended by the CDC, the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America. A positive result on the first step (a skin test) means the patient is at risk for a penicillin allergy. If negative, the skin test is usually followed by an oral penicillin class challenge to safely rule out an IgE-mediated penicillin allergy.v
Better stewardship and better care
Current literature supports the role of penicillin allergy skin testing in various practice settings to help improve patient care by reducing the use of alternative antibiotics. In fact, data from a recently conducted study showed that more than 90 percent of hospitalized patients who underwent penicillin allergy testing were not allergic, and therefore had the label removed from their patient health records.iv
It's important to build awareness that skin testing for penicillin allergies is a valuable tool to optimize antibiotic utilization. This will ultimately enable healthcare providers to prescribe less expensive, less toxic, and more appropriate antimicrobial agents—all of which enhance antibiotic stewardship initiatives while benefitting patient care.
About the Author:
Dr. Justin Chen is an Allergy and Immunology Physician at Parkland Health and Hospital System in Dallas, Texas.
i Macy, Eric, et al. Health Care Use and Serious Infection Prevalence Associated with Hospitalized Patients. JACI. Vol. 133, No. 3. March 2014.
ii CDC. Antibiotic Resistance Threats in the United States. Atlanta, GA: 2013. Available at http://www.cdc.gov/drugresistance/threat-report-2013/.Centers for Disease Control (CDC) Get smart for healthcare website. http://www.cdc.gov/getsmart/healthcare/. Last accessed January 2017.
iii American Academy of Allergy Asthma & Immunology. Penicillin Allergy FAQ. https://www.aaaai.org/conditions-and-treatments/library/allergy-library/penicillin-allergy-faq. Accessed January 2017.
iv Chen, Justin R, et al. A Proactive Approach to Penicillin Allergy Testing in Hospitalized Patients. J Allergy Clin Immunol Pract 2016; in press.
v CDC. Get Smart Penicillin Fact Sheet. Atlanta, GA: 2016. Available at https://www.cdc.gov/getsmart/week/downloads/getsmart-penicillin-factsheet.pdf
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