Allergy testing during pregnancy could prevent unnecessary antibiotic exposure

Women who have a documented history of penicillin allergy should undergo allergy tests during pregnancy to avoid exposure to potentially less effective broad-spectrum antibiotics, according to a small study presented at ACAAI 2021.

“Of the pregnant women who underwent skin testing for evaluation of penicillin allergy, 32 percent avoided additional exposure to oral or intravenous antibiotics during the duration of pregnancy and thus decrease[d] the risk for infant morbidity related to antibiotic administration during pregnancy,” said study author Dr Benjamin Wang from Oregon Health and Science University, Portland, Oregon, US.

Researchers of this retrospective study identified 32 pregnant women who had reported a history of penicillin allergy when they attended an academic allergy clinic over a two-and-a-half-year period. Twenty-five women who underwent skin testing for penicillin allergy were included. Only women who tested positive for Group B streptococcus (GBS) or who had another requirement for penicillin would be required to undergo a graded oral amoxicillin challenge.

All 25 women who underwent skin testing for penicillin allergy tested negative in this test. [ACAAI 2021, abstract P175]

Eight women had uncomplicated pregnancies and did not require penicillin treatment throughout their pregnancies. Two women required antibiotic treatment prior to undergoing a graded oral amoxicillin challenge due to unexpected skin lacerations that occurred during vaginal delivery.

Thirteen women tested positive for GBS, underwent both skin testing and oral amoxicillin challenge, and were given penicillin during labour.

The remaining two women were lost to follow-up prior to delivery.

According to a report by the US Centers for Disease Control and Prevention (CDC), while 10 percent of the population may have a history of allergy to penicillin, many do not actually have IgE-mediated reactions and less than 1 percent of the population is actually allergic to penicillin. Furthermore, about 80 percent of individuals with IgE-mediated penicillin allergy lose their sensitivity after 10 years. [https://www.cdc.gov/antibiotic-use/community/pdfs/penicillin-factsheet.pdf, accessed 10 November 2021]

The use of broad-spectrum antibiotics that are commonly used as alternatives to penicillin can increase the risk of antibiotic resistance. As such, identifying individuals without penicillin allergy could reduce the use of broad-spectrum antibiotics, and subsequently, antibiotic resistance. 

“Evaluation of pregnant women carrying a penicillin allergy label may reduce the risk for adverse events associated with the use of broad-spectrum antibiotics and improve antibiotic stewardship,” said Wang.

“Our penicillin allergy protocol may reduce antibiotic exposure through avoidance of oral antibiotic challenges in pregnant women if they do not have a clear indication for penicillin,” he said.

“Penicillin allergy testing is important for anyone who was given a penicillin allergy label as a child, and still carries it as an adult,” said Professor Mariana Castells from Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, US, and chair of the ACAAI Task Force on Drug Allergy.

“A pregnant woman with GBS may need penicillin for treatment. If she is labelled as allergic, she will be offered a less effective, and possibly more harmful antibiotic. It is important to have penicillin de-labelling ahead of the need for penicillin,” she continued.