In North America and Europe, penicillin allergy is the most common drug-allergy label.1 Carrying a penicillin-allergy label, which has recently gained more attention in health care systems, leads to suboptimal outcomes, increased use of broad-spectrum antibiotics, increased risk of adverse reactions, and increased cost of care.2,3 Despite the high rate of reported reactions, clinically significant immunoglobulin E (IgE)-mediated and T cell–mediated hypersensitivity reactions to penicillins are uncommon.2
Through the Choosing Wisely initiative of the American Board of Internal Medicine Foundation, the American Academy of Allergy, Asthma, and Immunology has issued a recommendation: “Don’t overuse non-beta lactam antibiotics in patients with a history of penicillin allergy without an appropriate evaluation.”4 The primary care physician (PCP) plays a critical role in the appropriate evaluation and accurate initial labeling of penicillin allergy. Furthermore, the PCP plays an integral part, in conjunction with the allergist, in removing the “penicillin allergy” label from a patient’s chart when feasible.
The history of penicillin and prevalence of allergy
History. Penicillin, the first antibiotic, was discovered in 1928 by physician and microbiologist Alexander Fleming when he observed that a mold of the Penicillium genus inhibited growth of gram-positive pathogens.5 Along with pharmacologist Howard Florey and chemist Ernst Chain, both of whom assisted in the large-scale isolation and production of the antibiotic, Fleming won the Nobel Prize in Physiology or Medicine in 1945 for this discovery.5
Antibiotics transformed the practice of medicine across a spectrum, including safer childbirth, surgical procedures, and transplantation.6 Penicillin remains first-line therapy for many infections, such as streptococcal pharyngitis,7 and is the only recommended medication for treating syphilis during pregnancy.8 Continued effectiveness of penicillin in these cases allows broad-spectrum antibiotics to be reserved for more severe infections. Regrettably, incorrect antibiotic allergy labeling poses a significant risk to the patient and health care system.
Epidemiology. As with all medications, the potential for anaphylaxis exists after administration of penicillin. Because its use is widespread, penicillin is the most common cause of drug-induced anaphylaxis. However, the incidence of penicillin-induced anaphylaxis is low9: A 1968 World Health Organization report stated that the rate of penicillin anaphylaxis was between 0.015% and 0.04%.10 A more recent study reported an incidence of 1 in 207,191 patients after an oral dose and 1 in 95,298 after a parenteral dose.11 The most common reactions to penicillins are urticaria and delayed maculopapular rash.8
In the United States, the prevalence of reported penicillin allergy is approximately 10% (estimated range, 8% to 12%)3,12-15; among hospitalized patients, that prevalence is estimated to be as high as 15%.13,15 However, the prevalence of confirmed penicillin allergy is low and has decreased over time—demonstrated in a longitudinal study in which the rate of a positive skin test fell from 15% in 1995 to 0.8% in 2013.16,17
Studies have confirmed that as many as 90% of patients who report penicillin allergy are, in fact, able to tolerate penicillins.14,18-20 This finding might be a consequence of initial mislabeling of penicillin allergy; often, adverse reactions are documented as “allergy” when no risk of anaphylaxis exists. Furthermore, patients can outgrow IgE-mediated penicillin allergy because the presence of penicillin IgE antibodies wanes over time.14,15
Continue to: Consequences of mislabeling