Delabeling penicillin allergy to improve syphilis care

About 10% of Americans believe they are allergic to penicillin, and approximately 90% of those patients are not actually allergic. As a result, those with the penicillin allergy label are often prescribed more toxic, dangerous and expensive antibiotics that might not be necessary or effective. A new study being presented at this year's American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting in Boston showed that syphilis patients labeled as penicillin allergic who are low risk should be delabeled to avoid treatment failure and other negative health consequences.

The number of people with untreated syphilis in the United States is at its highest since the 1950s, and penicillin is the preferred, most effective antibiotic for syphilis. With the goal of delabeling patients with syphilis who believed themselves to be allergic to penicillin, we collected data on demographics, syphilis stage, results of penicillin allergy testing, use of second-line treatment, healthcare utilization and use of penicillin after delabeling, and clearance of syphilis. Importantly, among those who came to us for penicillin allergy testing, we noticed a pattern in which more than half had failed other treatments, doxycycline in particular, before penicillin allergy testing was even considered."

Cosby Stone, MD, MPH, allergist, senior author of the study and ACAAI member

Of the 12 patients identified, 12 out of 12 were ultimately delabeled of their penicillin allergy. Nine of 12 had documented subsequent penicillin treatment, while 3 of 12 had incomplete histories or lost follow up. Of the 9 who received penicillin, 5 had clearance, 3 had failed clearance (2 for reinfection, 1 for unknown reasons), and 1 had unknown clearance outcome.

The authors conclude that most patients labeled as penicillin allergic should have their allergies evaluated as quickly as possible after a syphilis diagnosis and should be aggressively delabeled to avoid treatment failure, increased healthcare utilization, and negative public health consequences.