An Agreeable Girl With a Stubborn Rash

ANSWER
The correct answer is impetigo (choice “a”). Impetigo is almost always secondary to another condition, such as contact or irritant dermatitis, eczema, or dry skin.

DISCUSSION
Impetigo is a superficial bacterial infection usually caused by a combination of strep and staph organisms. It requires a break in the skin to provide a point of entry for the organisms. In young children, scratching and picking at eczema, along with lip licking, exacerbate the barrier-breaching process.

The organisms that cause impetigo are typically benign, but this was not always the case. Prior to WWI, certain strains of strep were capable of triggering an immune response that resulted in kidney damage. These “nephritogenic” strains of the Streptococcus family caused acute post-streptococcal glomerulonephritis (Bright disease), which, at that time, killed thousands each year. Fortunately, these strains are rare now.

In the pre-antibiotic days, when the average person bathed once a week, impetigo was highly contagious and serious enough that whole households were quarantined because of it.

Today, impetigo, once diagnosed, is relatively simple to manage. Mild cases can be treated with application of mupirocin ointment or cream three times a day. In this particular case, a 10-day course of an oral antibiotic (trimethoprim sulfa) was added, and the rash rapidly cleared.