Sarcoptes scabiei
Causes scabies. Presents as itchy bodily areas (e.g., the hands) classically in patients living in close quarters like homeless shelters or group homes.
Causes “linear burrows,” although these might just appear like red dots on the skin in USMLE images.
Tx = topical permethrin.
What USMLE will do is show you above image + tell you a 45-year-old man was living in a homeless shelter for 4 months + topical anti-fungals didn’t work; what is the treatment –> answer = topical permethrin.
Bacterial superinfection with S. aureus can occasionally occur on scabies lesions. As I talk about in the gram (+) cocci module regarding S. aureus, infections are often treated with oral dicloxacillin or cephalexin.
Pediculosis capitis/corporis
Pediculosis capitis = head lice.
Pediculosis corporis = body lice.
The names of the organisms are the same as the conditions.
The main point here is that you are merely aware that pediculosis is the medical term for lice, since you’ll see it sometimes as an answer choice on USMLE.
Tx = topical permethrin (same as scabies).
Cimex lectularius
Causes bed bugs.
Presents as very itchy clusters of erythematous lesions on the trunk and limbs in patients who’ve slept in dodgy locations or hotels.
Can occur if someone brings a mattress in off the street. Sounds dumb, but we’re talking about actual demographics here.
NBME has an image of this in one of its questions:
Treatment is supportive and involves not scratching the lesions. Occasionally calamine or steroid cream can be applied to reduce itching.
