Spider Bites vs MRSA Infections

Spider Bite or Staph? See the Doctor for Any Lesion That Doesn't Go Away

Pediatrics dermatologist with patient
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Methicillin-resistant Staphylococcus aureus (MRSA) skin infections are becoming more and more common. And surprisingly, these MRSA lesions are sometimes confused with spider bites, since they can often look the same.

In fact, a classic sign of a 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 a crust or an area of necrosis (dead skin)

    MRSA - A Staph Infection that is Resistant to Antibiotics

    MRSA infections are seen with increasing frequency. They were once limited to people with weak immune systems and seen mostly in patients in hospitals and nursing homes. MRSA is now affecting even healthy adults and children. The CDC says anyone can get MRSA through direct contact with other people or sharing personal items. This means that schools, daycares, and gyms are areas where MRSA can be spread due to the sharing of equipment and close contact with other people in those facilities.

    Children and adults can carry MRSA in their nose while they are healthy and have no symptoms or infection from it. The CDC says as many as one in 50 people are carriers. As they are not sick from it, you never know who might be a carrier.

    The trouble comes when MRSA causes a skin infection. It can be difficult to treat as it is resistant to the most commonly used antibiotics.

    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:

    • Don't be 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 another 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 a 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, so they automatically think about 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.

    Photos of Spider Bites and MRSA Infections

    If you would like to see photos of spider bites and MRSA to see how similar they appear, you can visit these pages. Warning, the photos can be graphic and may be disturbing to you.

    Spider Bite Photos: First Aid Expert Rod Brouhard, EMT-P has collected dozens of photos of spider bites.

    Photos of MRSA Infections: These photos are from the CDC and show skin infections of MRSA. The CDC notes that these infections often first look like spider bites.

    That should be a caution to have any suspicious lesion looked at by a doctor.


    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.

    General Information About MRSA in the Community, Centers for Disease Control and Prevention. 

    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.

    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.