FRIDAY, Sept. 11, 2026 (HealthDay News) — The microscopic organisms that live on a baby’s skin could provide an early warning sign of eczema or food allergies, a new study says.

Babies about to develop eczema or food allergies experience distinct changes in the trillions of microbes that form the skin’s microbiome, researchers reported recently in the journal Allergy.

Specifically, higher levels of staph bacteria on babies’ skin at 2 to 3 months old is associated with later development of eczema accompanied by food allergies, researchers found.

“We actually saw skin microbiome changes in infants who hadn't even been diagnosed with these diseases yet,” said lead researcher Zeyang Shen in a news release.

“That was one of the most exciting findings because those changes could potentially be used as biomarkers to help clinicians diagnose disease earlier,” Shen said. He is an assistant professor of molecular biosciences at Washington State University.

Eczema can affect up to 20% of children, with most cases occurring during the first year of life, researchers said in background notes.

A person’s skin acts as a natural barrier against harmful germs, according to the American Academy of Dermatology. Eczema rashes occur when that barrier is diminished, leading to inflamed, irritated and itchy skin.

Childhood eczema alongside food allergies can set kids up for other allergic diseases like asthma later in their lives, researchers said.

For the new study, researchers analyzed more than 1,000 skin swabs from 429 infants, including samples collected at 2 to 3 months old and again at age 1. Advanced DNA sequencing allowed researchers to identify the microbes living on infants’ skin.

It turned out that infants with elevated levels of Staphylococcus bacteria had a higher risk of developing eczema and food allergies by the time they turned 1.

Babies with eczema also were more likely to have mutations in the FLG gene, one of the major genetic risk factors for the disease, researchers said. The gene helps produce filaggrin, a protein that maintains the skin’s protective barrier.

Babies with FLG mutations were also likely to have lower levels of Streptococcus species on their skin and higher levels of other organisms, researchers found.

Researchers also found substantial sharing of microbes between moms and their babies.

“The microbial strains are very much shared between infants and their mothers,” Shen said. “That gives us another layer to this story, suggesting that the people we live around and continuously exchange microbes with could also be contributing to our skin microbiome.”

Researchers will continue to track these children, to see whether their early-life skin microbes are linked to later health problems like asthma.

“Today, these diseases are diagnosed after symptoms appear,” Shen said. “If we can validate these microbial signals in other groups of children, they could potentially serve as early biomarkers that help identify disease risk much earlier.”

More information

The American Academy of Pediatrics has more on childhood eczema.

SOURCES: Washington State University, Sept. 9, 2026; Allergy, Sept. 9, 2026