True Stories: How clean is your skin?

Mrs. Brooks brought Sara, 2, (names are fictitious) to my office.
Sara had a coppery red skin lesion over her diaper area, which turned out to be a fungal infection.

“I give Sara a bath every day, sometimes twice daily. I can’t believe she got this fungal infection,” the mother lamented.

“Mrs. Brooks, I gave her an antibiotic recently. That or a small scratch in the skin might have started the infection. Sara looks adorable and clean but human skin harbors billions and billions of bacteria, fungi and spores.”

“So all the baths I give don’t help her much?” she inquired.

“Let me explain,” I said.

Many kinds of bacteria thrive on our body surface and inside. The skin, eyes, nose, mouth, lower intestine, vagina and urethra harbor millions of bacteria of various varieties.

Each bacterial species occupies a particular part of the body and prefers to stay there. For example, streptococcus mitis and streptococcus salivarius thrive in the mouth and pharynx but not on the skin surface.

Over the skin as well, distinct types of bacteria occupy certain areas of the skin just as different ethnic groups of people reside in certain sections of a city.

About 600 species of bacteria live on the surface of the skin and 99 percent of them have never been cultured in the laboratories.

We do not know the identity of these bacteria, their numbers or the purpose of their presence.

We need to know more about them in order to understand skin diseases and their treatment.

Dr. Julie Segre, a senior investigator in genetics and molecular biology, and coworkers at the National Human Genome Institute studied the bacterial flora on the skin by analyzing their ribosomal RNA.

As eczema is common near the elbow area, the investigators took scrapings, swabs and punch biopsies of the skin to study the bacterial RNA from that place.

They found 113 varieties of bacteria at the site.

Among them, 10 bacterial species formed 90 percent of the crowd.

For example, pseudomonas species, which is found in the soil, water and decaying organic material, is found at the elbow.

Sometimes doctors wonder how a pseudomonas infection has infiltrated into an ICU setting.

This is because people have the germ on their elbow and when immunity is low, the infection can enter the respiratory tract or blood stream.

Another species, janthinobacteria that are commonly found in the soil is found at the elbow and other parts of the skin.

In another study, Gracie EA and others have found 19 species of known bacteria such as staphylococcus epidermidis and propionibacterium acnes and 13 entirely new species over the forehead skin.

The belly button, too, carries multiple bacteria; that is why body piercing at this site gets infected easily.

A couple of Surprises: deeper layers of the skin harbored 100 times more bacteria per square centimeter than on the surface and the areas between the toes were sparsely populated by bacteria.

Pediatricians often notice candidial fungal infections after treating a child with antibiotics.

The antibiotics remove or alter the normal bacterial flora of the skin and mouth and facilitate the growth of fungi and antibiotic-resistant bacteria.

If we know more about the normal bacteria that reside over the skin and other parts of the body, and understand how they protect against infections then perhaps we can re-colonize the area with them instead of using yet another drug to treat the antibiotic-induced infection.

I prescribed Sara an antifungal ointment, which cured the skin lesion.