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Pharmacists can help identify most appropriate antibiotics for patients allergic to penicillin
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Pharmacists can help identify most appropriate antibiotics for patients allergic to penicillin

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Penicillin Allergy

Olivia C. Welter, PharmD

An article published on January 21, 2023, in AJHP reveals some welcome findings: When pharmacists are involved in antibiotic selection, hospitals can potentially save money and patients are less likely to be prescribed undesirable second-line therapies.

Past studies have found that risk of infection increased when an alternative, non-β-lactam preoperative antibiotic was given to patients undergoing surgery. Most often, clinicians choose this route when patients report a penicillin allergy.

Many pharmacists are all too familiar with the issues that a penicillin allergy label can cause. Most notably, patients who believe they are allergic to penicillin may not even react negatively to the antibiotic. In fact, Mayo Clinic noted that half of those with this type of allergy will outgrow it within 5 years, and 80% will outgrow it within 10 years.

Despite this, many patients either are unwilling or unqualified to undergo penicillin allergy testing. To make matters worse, over half of all hospitals in the United States lack access to penicillin allergy testing. This complicates treatment plans for infection prevention, as β-lactam medications are often first-line options.

These findings demonstrated that pharmacists can help lead the charge on antimicrobial stewardship for surgical patients by assessing risk for severe allergic reactions. Additionally, penicillin-allergic patients deemed to be low risk were able to safely receive first-line β-lactam prophylaxis and subsequently be de-labeled for penicillin allergy.

a medical ID bracelet identifying a penicillin allergy

Perioperative antibiotic algorithm

Researchers documented a quality improvement algorithm for surgical patients used by the Mayo Clinic in Jacksonville, FL. Once broad spectrum antibiotics were ordered preoperatively for these patients at Mayo Clinic, pharmacists were tagged to review each patient’s chart for allergy and antibiotic history. Pharmacists then determined whether a patient’s recorded penicillin allergy posed a high or low risk of severe reaction to the medication.

Patients were placed in a high-risk category if they previously experienced reactions like anaphylaxis, severe cutaneous adverse reactions, and serum sickness, among others. These patients were prescribed a non-β-lactam antibiotic preoperatively to avoid any repeats of a severe allergic reaction.

Patients’ penicillin allergies were considered to be low risk if the documented reaction to penicillin involved a rash, itching, general intolerance, or even if there was not a documented reaction included in the chart at all. Patients at low risk were given cefazolin as their surgical infection prophylaxis.

According to the algorithm, all patients with a recorded penicillin allergy, regardless of their risk stratification placement, were referred to the hospital’s allergy team for follow-up penicillin allergy testing.

Algorithm impact

The study authors noted in their discussion that over a 3-month period, the algorithm caused usage of cephalosporins preoperatively in patients with a penicillin allergy label to grow 3-fold. Additionally, second-line antibiotic usage decreased 1.5-fold.

According to several studies referenced in the article, limiting use of second-line therapies while prioritizing β-lactam is a reliable preoperative prescribing strategy to keep risk of infection low and mitigate potential for antibiotic resistance. This study at the Mayo Clinic, in particular, found that following the algorithm and engaging pharmacists in chart reviews contributed to cost savings, as well.

The last step in the algorithm is to refer patients for allergy testing, and the study authors found that 80% of patients who were evaluated postoperatively by an allergy provider had their penicillin allergy label removed. This means that a majority of patients who initially presented for their surgery thinking they were allergic to penicillin had actually outgrown the allergy entirely. ■



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