Atopic dermatitis is a complex multifactorial disease, including bacterial skin dysbiosis and defective skin barrier. It is characterized by impaired skin barrier function which may precede clinical skin lesions in infants.

A recent study published in J & J (BABY CARE) showed that Staphylococcus aureus colonizes the lesional and non-lesional skin of atopic dermatitis (AD) patients.

The significance of altered bacterial colonization for AD is demonstrated by the positive correlation between AD severity and density of cutaneous S. aureus colonization. Skin emollients rehydrate the skin, reduce the severity of AD, prevent the development of eczema and improve skin barrier function – thereby forming an integral component of AD treatment. In addition, emollient and its components alter skin bacterial growth and survival.

To determine the impact of emollients on 23 infants at risk for developing AD, six-month-old infants with a family history of atopy were randomized to receive (emollient group; n=11) or not receive (control group; n=12) emollients. Comparison of samples based on skin barrier parameters, AD development and bacterial 16S ribosomal RNA gene sequences of cheek, dorsal and volar forearm samples were done.

The findings revealed that:

• Streptococcus salivarius proportion was higher in the emollient versus control group at all sites.
• The number of bacterial taxa in the emollient group was higher than in the control group at all sites. While the emollient group had a lower skin pH than the control group.
• S. salivarius proportion appeared higher in infants without AD compared to infants with AD.
• Cheek samples in both, the emollient and control groups, had the fewest number of different bacterial taxa as compared to the dorsal forearms and volar forearms.
• Additionally, Staphylococcus aureus and Streptococcus salivarius proportions are inversely correlated with the severity of AD.

From the results, it was concluded that the decrease in skin pH and increase in S. salivarius proportion after long-term application of emollient in infants at a risk for developing AD contributes to the preventive effects of emollients in high risk infants. The lower skin pH and immunomodulatory effects of S. salivarius may contribute to the therapeutic effects of emollient use in AD patients. Furthermore, the proportion of Streptococcus salivarius is higher in infants due to long-term application of emollients. Meanwhile, the proportions of Streptococcus salivarius and Staphylococcus aureus are inversely correlated with the severity of AD.

Hence, emollient application positively alters skin barrier and microbes in infants at risk for developing AD positively

Source: J & J (BABY CARE). 2019 Nov.