Does it really matter if this is not a spider bite? The patient sought help by a doctor and received antibiotics. Spider bite or not, it is starting to heal.
It does indeed matter whether this is a spider bite or something else. Spider bites cause their damage with venom -- which requires a different treatment than bacteria. If the bacteria happens to be MRSA, the treatment is different still.
Doctors make the same types of mistakes the rest of us do. If they regularly hear about spider bites, they'll more likely see spider bites where none exists. If doctors are encouraged to consider other causes for wounds like this, they'll rule out other possibilities. You can set the tone when you arrive at the doctor's office.
Tell your doctor you have a spider bite, and he or she will be working with that in mind. On the other hand, if you tell your doctor you have a sore and you don't know how it got there, he or she will have to consider all the possibilities.
Have a spider bite you want to share? Submit a picture of your spider bite.
Want to talk about spider bites? Ask others and see more bites on the First Aid Forum.
de Souza, A.L., et al."Loxosceles venom-induced cytokine activation, hemolysis, and acute kidney injury." Toxicon. Jan 2008.
Pagac, B.B., et al."Skin lesions in barracks: consider community-acquired methicillin-resistant Staphylococcus aureus infection instead of spider bites." Military medicine. Sep 2006.