Allergy to penicillin — at least as reported by patients — is both common and a challenge to clinicians, who must then decide what to prescribe for patients with infections. Several presentations on penicillin allergy were scheduled for presentation at the American Academy of Allergy, Asthma, and Immunology annual meeting, cancelled because of concerns surrounding COVID-19 coronavirus. Here we review some of those abstracts as published by the academy.

How Reliable Is That Old Diagnosis?

Many patients who self-report or have previously been designated as being allergic to penicillin actually lose that label when they are re-tested, researchers found.

Hiral Thakrar, MD, of Scripps Green Hospital in La Jolla, California, reported that 34 of 38 patients who had been considered by records as allergic to penicillin had negative skin tests to penicillin challenges (Abstract #176). One patient had a positive skin test, and the other three had negative skin tests, but were unable to complete an oral challenge test.

“Penicillin allergy is the most common drug allergy reported, with a prevalence of 8%-12%,” Thakrar noted. “Over 90% of these patients are not truly allergic.”

She and her colleagues went through the records of patients who were identified in their charts as being allergic to penicillin, amoxicillin, Augmentin, or ampicillin upon admission to the surgical unit at Scripps Green Hospital. At discharge the patients were referred to the allergy clinic.

From September 2018 to June 2019, a total of 316 referrals were made, but just 40 of the 316 patients scheduled a consultation. Two of those patients did not have time for testing on the day of consultation, providing 38 patients for the study, Thakrar reported.

“Only 13% of patients referred to our allergy clinic for penicillin testing from the surgical unit scheduled a consultation,” she said. “About 97% of those who did undergo penicillin skin testing were negative. Poor referral follow-through warrants further investigation, although we hypothesize that the reason is that many patients are focused on recovering from surgery and are unfamiliar with the indications and benefit of penicillin testing.”

“We have begun sending all referred patients an information letter from our allergy clinic 3 weeks after their discharge with hopes to improve rates of referral follow-through,” Thakrar added. “Secondary intervention data is currently being collected.”

Similar Results in Young Women

In Abstract #171, Heather Stern, DO, of Penn State Health, Milton S. Hershey Medical Center in Hershey, Pennsylvania, reported that when the results were revisited, 32.2% of patients who had been labeled as having an allergy to penicillin were cleared of their penicillin allergy by either allergy testing or history.

“Unverified penicillin allergy during pregnancy is associated with significant morbidity including longer hospital stays, increased risk of cesarean delivery, and specifically in [group B Streptococcus]-positive women, increased frequency of alternative antibiotic use with higher rates of adverse drug reactions,” Stern noted.

She and her colleagues performed a retrospective chart review of female patients seen in the center’s Pediatric Allergy/Immunology clinic from 2010 to 2018 who had a listed penicillin allergy at the time of their initial visit. A total of 180 patients met the inclusion criteria, of which 134 (74.4%) had their penicillin allergy reviewed.

For 111 of these patients (82.8%), the review occurred at the first visit. Seventy-five patients (55.9%) had definitive recommendations made at one of their visits. In addition to the 58 patients who were cleared of their penicillin allergy designation, 11 additional patients did not follow through with recommendations for testing.

In patients ages 11 to 18, penicillin allergy was reviewed for 29 of 39 patients (74.3%); of these, 17 patients (43.5%) had their penicillin allergy cleared, three did not proceed with the recommended plans, and seven had plans to assess in the future, Stern reported.

“It is critical to target the preteen/adolescent female population regarding penicillin allergy evaluation,” she wrote. “Our findings suggest that this population is under-evaluated in our clinic. As such, factors that limit this assessment need to be explored, and more innovative methods to ensure timely penicillin allergy evaluation in this group are necessary.”

Allergy Education for Residents

Another group of researchers suggested that educating residents about penicillin allergy in patient records, and the high degree of mistaken labeling of patients as being allergic, might be able to change the situation (Abstract #174).

Participation in an educational session appeared to improve residents’ knowledge about penicillin allergy and their comfort level in discussing penicillin allergies with patients, and also in increasing the likelihood of referral of patients to allergists, reported Lauren Kaminsky, MD, PhD, a resident at Hershey Medical Center.

“Documented penicillin allergy results in altered antibiotic regimens for patients, leading to increased side effects, antibiotic resistance, and increased healthcare costs,” Kaminsky wrote in her abstract. “Penicillin allergy is commonly listed in the medical record, but the likelihood of [immunoglobulin E]-mediated allergic reactions is low.”

The goal of the study was to see if an educational session targeting internal medicine residents would move the needle in addressing the likelihood of recommending penicillin allergy evaluation. The session was designed for the residents and included a small group discussion of a review article. A pre-survey and post-survey were distributed at the time of the educational session. Questions were designed to examine knowledge, comfort level, and clinical practice regarding penicillin allergy.

Kaminsky reported that after the session, residents demonstrated improved knowledge about penicillin allergy, with correct answers about contraindications to penicillin allergy testing improving from a mean of 3.1/5 to 4.9/5. Comfort level in discussing penicillin allergy also increased, from an average of 2.7/5 to 4.3/5. The likelihood of patient referral to allergists for further penicillin allergy testing increased from a mean of 2.3/5 to 3.9/5.

“An educational session on penicillin allergy for internal medicine residents is effective at improving their knowledge and comfort level in managing, counseling, and providing appropriate recommendations for testing in patients with documented penicillin allergy,” Kaminsky wrote. “This study may provide a sustainable educational method on penicillin allergy evaluation and testing. We plan to investigate the impact over an extended period of time.”

‘Can be Outgrown, but More Often Misdiagnosed’

Asked for her perspective about penicillin allergy in general, Blanka Kaplan, MD, director of the Drug Allergy and Desensitization Center at Northwell Health in Great Neck, New York, said that in some cases, penicillin allergy can be outgrown, but more commonly, it is misdiagnosed.

“People get rashes with viral and bacterial infections,” Kaplan told MedPage Today. “Sometimes a combination of the antibiotic and infection causes rashes. If a person gets a rash while taking the antibiotic, he or she is diagnosed with penicillin allergy and the penicillin allergy label is carried for years and decades. Recent data shows that more than 95% of people with a label of penicillin allergy are in fact not allergic to penicillin.”

“Here at Northwell we have a dedicated penicillin allergy clinic, designed to de-label people who are misdiagnosed as being allergic to penicillin,” she continued. “It has been clearly shown that the diagnosis of penicillin allergy leads to use of alternative antibiotics. These alternative antibiotics are broader spectrum and lead to more complications, antibiotic resistance, and higher costs.”

Last Updated March 17, 2020