Spider Bites vs. MRSA Infections

See the doctor for any swollen lesion that doesn't go away

Methicillin-resistant Staphylococcus aureus (MRSA) skin infections are becoming more and more common. These MRSA lesions are sometimes confused with spider bites since they can often look the same. It's important to know about the similarities so you know when to get help.

Pediatrics dermatologist with patient
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Similarities of MRSA and Spider Bites

Since spider bites and MRSA infections have different treatments, it's important to know they look similar and when you should see a doctor. Don't blame a lesion on a spider bite unless you actually saw a spider bite your child, as that could bias your doctor's diagnosis.

A classic sign of infection with MRSA 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)

When to See a Doctor

See your pediatrician if any bite, pimple, or rash continues to get red and swollen after a few days of home treatment.

Get treatment right away if you suspect MRSA infection due to a red, swollen, painful area that's full of pus or draining. Don't delay treatment for what could be a treatment-resistant staph infection because it could be a spider bite.

Most pediatricians know about this common misidentification, so they automatically think about MRSA when someone complains of a spider bite.

Antibiotic Resistance

MRSA infections were once limited to people with weak immune systems and seen mostly in hospital and nursing home patients. However, they're becoming more common and can affect even healthy adults and children.

The CDC says anyone can get MRSA through direct contact with other people or sharing personal items.

Schools, daycares, and gyms are areas where MRSA can easily spread due to shared equipment and close contact with other people. You can carry MRSA in your nose even when have no symptoms of infection.

In fact, the CDC says 5% of hospital patients carry MRSA on their nose or skin. As they're 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's resistant to common 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.

Photos: Spider Bites and MRSA

If you'd 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.

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Article Sources
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  1. Cleveland Clinic. Methicillin-resistant Staphylococcus aureus (MRSA): Diagnosis and tests. Updated November 10, 2916.

  2. Centers for Disease Control and Prevention. Methicillin-resistant Staphylococcus aureus (MRSA). Updated June 26, 2019.