AD May Be a Risk Factor for GBS Colonization in Pregnancy

Pregnant women with atopic dermatitis (AD) are more likely to be colonized with group B streptococcus (GBS), compared with other pregnant women, results from a large cross-sectional study suggest.

“The rate of GBS colonization among pregnant females with a history of AD has not been previously reported, but AD could be a risk factor for maternal carriage of GBS,” corresponding author David J. Margolis, MD, PhD, of the department of dermatology at the University of Pennsylvania, Philadelphia, and colleagues wrote in the study, which was published as a letter to the editor online in the Journal of Investigative Dermatology. “GBS reporting in a large administrative database represents a unique opportunity to conduct a population-based evaluation of GBS carriage with AD. Understanding this association could expand our understanding of microbial changes associated with AD,” they noted.

To determine if an association between GBS and AD in pregnant women exists, the researchers performed a cross-sectional study using a random sample from an Optum administrative database of pregnant women who had vaginal deliveries between May of 2007 and September 2021. The primary outcome of interest was the presence of GBS based on American College of Obstetricians and Gynecologists–recommended codes for GBS during 36 0/7 to 37 6/7 weeks of pregnancy. They used descriptive statistics to summarize categorical and continuous variables as proportions and means, and logistic regression to examine the association between AD and GBS status.

The cohort included 566,467 pregnant women with an average age of 38.8 years. Of these, 2.9% had a diagnosis of AD or a history of AD, and 24.9% had diagnoses of asthma, seasonal allergies, or both. Women with AD had an increased odds ratio of asthma (OR, 2.55), seasonal allergies (OR, 3.39), or both (OR, 5.35), compared with those without AD.

GBS was reported in 20.6% of the cohort. The median time of follow-up for those with and without GBS was 494 days and 468 days, respectively (= .134). Among the women with AD, 24.1% had GBS, compared with 20.51% of the women without AD (<.0001), which translated into an OR of 1.23 (95% confidence interval, 1.18-1.27).

Among the women with GBS, the OR of asthma was 1.08 (95% CI, 1.06-1.10) and was 1.07 (95% CI, 1.05-1.09) among those with seasonal allergies. When adjusted for potential confounders, these findings did not change substantively.

“It is not apparent why pregnant females with AD are more likely to specifically carry GBS,” the authors wrote. “However, several studies have shown that individuals with AD are more likely to carry [Staphylococcus] aureus and that individuals with AD might be deficient in host defenses against S. aureus and other pathogens,” they added.

“Individuals with AD frequently receive antibiotics as part of their AD treatment and this might alter their resident microbiome. Carriage rates may be enhanced by the inhibition of an important barrier protein called filaggrin (FLG) and FLG loss of function genetic variation is known to decrease barrier proteins thought to inhibit the colonization of S. aureus and other pathogens,” the researchers wrote.

They acknowledged certain limitations of their study, including its reliance on an administrative database that does not contain information on past disease.

Asked to comment on the results, Adam Friedman, MD, professor and chair of dermatology at George Washington University, Washington, who was not involved with the study, characterized AD as “the poster child for cutaneous dysbiosis – an altered petri dish, so to speak, [that] facilitates survival of the few, leading to decreased microbial diversity that can both enable potential pathogen invasion and immune dysregulation.”

Though it’s not surprising that pregnant AD patients have dysbiosis, the focus on GBS, “which can be a bad actor in the perinatal period, is an interesting connection,” he said. “Will this change practices? Pregnant women should be screened for GBS regardless, but maybe more attention or counseling can be offered to AD patients about the importance of screening. Would decolonization regimens be employed early in pregnancy? This study can’t answer that but certainly raises good questions.”

Margolis disclosed that he is or recently has been a consultant for Pfizer, Leo, and Sanofi with respect to studies of atopic dermatitis and served on an advisory board for the National Eczema Association. Another author disclosed receiving grants from companies related to work with AD; other authors had no disclosures. Friedman reported having no relevant disclosures.

This story originally appeared on, part of the Medscape Professional Network.

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