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Spider Bites vs MRSA

Pediatric Dermatology Basics


Updated June 11, 2014

Spider bites are often mistaken for MRSA skin infections.

Spider bites are often mistaken for MRSA skin infections.

Photo courtesy of the CDC

Methicillin-resistant Staphylococcus aureus (MRSA) skin infections are becoming more and more common these days.

And surprisingly, these MRSA lesions are sometimes confused with spider bites, since they can often look the same.

In fact, a classic sign of an MRSA infection is that people will describe the area as looking like a spider bite:

  • a red, swollen, painful area on a child's skin
  • a central area that can have crust or an area of necrosis (dead skin)


MRSA infections are being seen with increasing frequency -- once limited to people with weak immune systems in hospitals and nursing homes, MRSA is now affecting even healthy adults and children. MRSA, while it is a type of staph bacteria that many healthy people can normally have on their skin, can be difficult to treat when it causes an infection. And while MRSA infections are sometimes limited to simple pimple-like infections, they can often become a much larger abscess or boil that needs to be drained.

Spider Bites vs MRSA

Since spider bites and MRSA infections have very different treatments, it is important to try and recognize which one your child has.

It can help if you:

  • aren't quick to blame a lesion on a spider bite unless you actually saw a spider bite your child, since that could bias your doctor's diagnosis.
  • see your pediatrician if any bite, pimple, or other rash continues to get red and swollen after a few days of home treatment.
  • see your pediatrician right away if you suspect that your child might have an MRSA infection (a red, swollen, painful area on his skin that is full of pus or is draining).

Most pediatricians know about the MRSA and spider bites connection now though, so they automatically think MRSA when someone comes in complaining of a spider bite. Still, you don't want to delay the treatment for a resistant staph infection because you are treating a spider bite that your child never really had.


A review of community-associated methicillin-resistant Staphylococcus aureus skin and soft tissue infections. Gorwitz RJ - Pediatr Infect Dis J - 01-JAN-2008; 27(1): 1-7.

The diagnosis of brown recluse spider bite is overused for dermonecrotic wounds of uncertain etiology. Vetter RS - Ann Emerg Med - 01-MAY-2002; 39(5): 544-6.

Reports of presumptive brown recluse spider bites reinforce improbable diagnosis in regions of North America where the spider is not endemic. Vetter RS - Clin Infect Dis - 15-AUG-2002; 35(4): 442-5.

Related Video
How to Treat Children's Bug Bites
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