I look forward to a response from others too. I've been on this health journey for a year now with my daughter who is 8 and a half. She has a waxing and waning of "tics" -- still, unsure what to call them. When they appeared full-blown, she had a negative throat culture. Until then, I'd never heard of PANDAS or even knew strep could cause these things. After a couple months, a neurologist who we couldn't get in to see right away (b/c I wasn't fast-tracked by my pediatrician) prescribed an antibiotic as he wanted to be sure that IF it was strep causing the tics, that it didn't go to her heart. The day after finishing the round of antibiotics, my daughter complained of a sore throat which turned out to be positive strep -- remarkable b/c up to this point she'd never had one. She was given a higher dose of antibiotics and by day 2 the tics were gone. They stayed away for a few months. Everyone I've talked to said that this was a fluke b/c she didn't have the positive throat culture the week before she started the antibiotics. They insist strep will only colonize in the throat. This includes my pediatrician, an infectious disease specialist at Boston Children's and the neurologist who specializes in tic and movement disorders at Children's. Meanwhile, her tics, although mild, have returned and no doctor will give antibiotics without a positive throat culture. I'm convinced there is something bacterial going on, but getting someone to help me find it has been difficult. Just last week I emailed Dr. Cunningham who, as you may know, is doing research as to what's happening in the brain in relation to PANDAS. If my doctors aren't willing to take it upon themselves to find out what is causing all this (they tell me not to worry, tics come and go in kids), I want to request specific tests to be able to rule out strep as the cause. She told me to have her throat, stool and vagina tested for streps A, B, C and G -- who even knew there were so many?? It is my hunch doctors don't check for all. I hope this helps you (although I know it isn't the info you're looking for) as it sounded like you may be headed down the same frustrating path I'm on with my daughter who doesn't have positive cultures from her throat and doesn't fall into a PANDAS diagnosis without the positive throat cultures.
Sidenote: Over the last year, I learned about functional medicine, doctors who look at the body as an interconnected system. We had all kinds of tests done (hormones, toxicity, etc.) My daughter, who has a peanut allergy and been to Boston Children's twice to be seen by an allergy specialist there never did IGg testing on her. The functional medicine doc did and the results showed high for gluten and dairy intolerance. My understanding is that although the intolerance may not be the cause of what's going on, it is possible that the body is working so hard on a daily basis to fight what it recognizes as toxic that when it needs to fight real sickness, the body goes into overdrive to fight and sends the nervous system out of whack. It has made me wonder what the correlation could be with kids who have PANDAS and other immune failure in the system with things like with food allergies. But that's another discussion thread..... I mention all this as I wonder if it would be worthwhile for you to explore functional medicine. http://www.functionalmedicine.org/about/whatis.asp I started with Dr. Hyman's book, The UltraMind Solution, which explains why and how we need to bring the body to optimal physical health for neurological and psychological health. That they are intimately related.