"Do you think I need to see a doctor about this?"
I hesitated briefly and my sister, also a nurse, jumped in, "Yes! That's ugly."
Ugly is an understatement. It was about 3cm (1.5 inches) across and elevated by nearly a half inch. Fiery red with a scabbed center, my hesitation was not about whether it should be seen, but how soon. ER or private physician?
"How long has it been there?"
"Yesterday. The spider bit me yesterday. It itched and I scratched it."
We also learned that it had oozed a thick, white, substance that was described as resembling yogurt. We learned that the pain was quite localized in the area of the lesion which had doubled in size since the previous day AND that the person had NO intention of changing plans for the evening which did not include the ER. I hope it doesn't do more than double again before it's treated.
I'm betting on CA MRSA - community acquired methicillin resistant staph aureus. Nasty bug, that one, and increasingly common. I hope I'm wrong. Better that than a brown recluse spider bite, though. Those cause significant tissue damage. The person did not think the bite was from a brown recluse, just a fairly large house spider and that it got infected after being scratched. If there had been a necrotic center, I'd have pushed for an ER visit that evening, but it was scabbed over, not necrotic, and not oozing.
In case you're curious, here are some links to MRSA infections and nasty spider bites:
Warning, they're all ugly.
Brown recluse bite -- note the necrotic area in the center. It's red, but not elevated.
Another brown recluse bite -- really ugly one on a hand. As an anonymous person says in the comments, this may or may not actually be a brown recluse bite. If it is, it's likely infection that has done most of the damage rather than brown recluse venom. Check out this link (no pictures) on the UC Riverside entomology site.
MRSA skin abcess -- very similar to the abcess I saw, but with no center scab -- and a little smaller
Spider bites can get infected, whether they're from a dangerous spider like the brown recluse, or a house spider. It is also possible, and doubtless more common, to have an infected hair follicle, or other skin lesion. The link above to the article about CA-MRSA includes a list of risk factors for otherwise healthy people which includes "close skin-to-skin contact, openings in the skin such as cuts or abrasions, contaminated items and surfaces, crowded living conditions, and poor hygiene."