Now let's cover impetigo. Impetigo is a bacterial infection involving the superficial skin.
Classically, we see yellowish crusted lesions. This is either caused by Staph aureus or
Streptococcus pyogenes and we can prevent this by handwashing and we treat it with
antibiotics. So, there are 2 types. There's the non-bullous and the bullous forms. First, the
non-bullous. These are superficial vesicles and pustules covered with honey-colored crust.
This is in contrast to the bullous, which is clusters and vesicles that are going to enlarge and
form very large blisters called bullae and these blisters are going to burst and then cause an
open wound then these will form honey-colored crust. So, these are caused by 2 bacteria.
Staph aureus, this is the most common that we see with bullous and nun-bullous forms. Then
we have Streptococcus pyogenes and we see this with the nun-bullous form. About 70% of
patients with impetigo have nun-bullous impetigo and about 30% have the bullous form. So
this is caused by a breakdown in the skin's barrier and the resultant secondary bacterial
infection. The skin breakdown can be from either a primary herpetic ulcer like herpes simplex
virus or VZV which is shingles. So, remember the patient may be a candidate for antiviral
therapy when they present and this should be considered in a patient who presents early in
their viral course. We commonly see impetigo after a patient has had a cold sore and these
lesions are typically found around the lips and around the nostrils and these are common sites
for herpetic eruptions. This is very common in the pediatric population. Patients with eczema
also get a break in their skin integrity and these bacteria can enter. So, risk factors; young
children ages 2 through 5 and children who attend daycare because they're sharing toys and
they usually play physically with each other and this is contagious, patients who are
immunocompromised and patients who live in a warm climate. So, this is transmitted with
direct contact with the lesions. The incubation is different based on the bacteria and Strep is
about 1-3 days after exposure and if it's caused by Staph it takes about 4-10 days.