Atopic dermatitis infections that persist

Dr. Orlow

Atopic dermatitis leads to Staphylococcus aureus colonization, one expert says.

“The barrier and immunologic defects of atopic dermatitis predispose those who suffer from the disease to colonization or infection by various bacteria, viruses and even fungi,” says Seth Orlow, M.D., PhD, chairman of the Ronald O. Perelman department of dermatology at New York University School of Medicine.

The bacterium most commonly associated with atopic dermatitis is S. aureus, which can be cultured from approximately 80% of the active lesions of atopic dermatitis.

“Even clinically uninvolved areas in people with atopic dermatitis often have an excess of S. aureus compared to the skin of a person without atopic dermatitis,” Dr. Orlow tells Dermatology Times, prior to his June presentation on atopic dermatitis and microbes at the 37^th Annual Advances in Dermatology meeting at NYU Langone Medical Center.

“Unfortunately, this has been misconstrued to mean that the S. aureus is itself the problem,” Dr. Orlow says. “But the preponderance of current evidence suggests that it is the atopic dermatitis that is the problem, and that treatment of the atopic dermatitis with anti-inflammatory medications like topical corticosteroids or calcineurin inhibitors reduces the carriage of S. aureus on the skin as the skin is normalized.”

Conversely, studies examining the effectiveness of topical and oral anti-Staph infections for atopic dermatitis, “have generally failed to show remarkable effects, excluding those patients who have overt, frank clinical infection like pustules or boils,” Dr. Orlow says. “Antibiotic use should be reserved for those patients with authentic infection,” Dr. Orlow says.

Overuse of topical and oral antibiotics by dermatologists “is an area of considerable current concern because of the increasing recognition that they can engender resistance by bacteria, both in and on that patient, as well as in the environment and in our society,” Dr. Orlow says. “It behooves us to reserve the use of antibiotics for cases where antibiotics are both truly needed and efficacious.” 

Some clinicians also misconstrue a surface culture positive for S. aureus in an atopic as evidence of infection, “when in fact colonization by S. aureus is a sine qua non of atopic dermatitis,” Dr. Orlow says.

Newer evidence

A recent study in the Journal of the American Academy of Dermatology that Dr. Orlow helped spearhead at NYU of children with atopic dermatitis, along with a prior study from the National Institutes of Health (NIH), concluded that treatment of the disease by topical corticosteroids or other means normalizes the microbiome in the skin of atopics, changing the microbiome from predominately S. aureus to a much more diverse set of bacteria that is closer in their nature and diversity to those found in normal skin.

Bleach baths containing dilute sodium hypochlorite have been used for decades as adjunctive treatments for atopic dermatitis.

“While some studies have shown a benefit to bleach baths, others have failed to do so,” Dr. Orlow says. “If there is a role for bleach baths, it is most likely in patients who have recurrent Staph infections of their skin, but to prevent infections rather than as treatment for the atopic dermatitis in and of itself.”

Molluscum is a highly prevalent viral skin infection that is self-limited, and children with atopic dermatitis are more prone to infection by the virus, according to Dr. Orlow.

“They may also develop many more molluscum lesions and the infection may persist longer than in children without atopic dermatitis,” he says.

In addition, molluscum may cause dormant atopic dermatitis to flare.

“Resolution of the molluscum, with or without physician involvement, will result in improvement of the dermatitis, insofar as it has been flared by the molluscum,” Dr. Orlow says.

A child with unilateral dermatitis in a popliteal or antecubital fossa should be carefully examined for the presence of molluscum, which is often detected.

A role for probiotics?

A new area of interest in the field of atopic dermatitis are probiotics.

“Given the normalization of the microbiome by the use of anti-inflammatory medication, and the lack of effect of antibacterial therapy in the average sufferer, it remains to be seen whether probiotics or the use of ‘good’ bacteria, topical or otherwise, will have a positive impact on the disease,” Dr. Orlow says.

Disclosure: Dr. Orlow reports no relevant financial disclosures.