The Lyme bacteria can actually be cultured (grown) from skin scraping of a bullseye rash.
I have better links on my computer (I'm sick in bed with my tablet right now, sorry), but here are these:
Lots of really good info on this page, but I was after this-
"When Dr. McDonald used a PCR primer that would amplify any strain of borrelia, he obtained positives from biopsies of bulls-eye rashes caused by tick bites..."
drcharlescrist.net/testing-for-borreliosis.html Fewer than 50% of patients with Lyme disease recall any rash. Although the erythema migrans (EM) or “bull’s-eye” rash is considered classic, it is not the most common dermatologic manifestation of early-localized Lyme infection. Atypical forms of this rash are seen far more commonly.
It is important to know that the EM rash is pathognomonic of Lyme disease and requires no further verification prior to starting an appropriate course of antibiotic therapy." http://www.ilads.org/lyme/about-lyme.php#sthash.yuTm8xqD.dpuf