It is not a sign of lupus but yes if you get uti's a lot and have trouble getting rid of them it can be as immune is down and opens you up for all sorts of things. I have sle and uti's are a problem for me as most of the time it takes me 2 to 3 times longer to get rid of them. Since kidneys are an issue they watch very careful what is going on and try to get rid of infections as soon as possible for me, but the body has it's own time table lol.
Clare is right about the cranberry drinks it does help to ward them off, not sure why but what works is a blessing. If you find you can't do cranberry there are lots of mixes:cran-apple, cran-grape, cran-cherry, and of course the cranberry. I also put mine over ice as it helps with the bitter taste.
Wish you the best in your fit of the infections and the other problems you may have. You might want to tell your doctor that you are seeing for a dx of lupus so he/she can keep track of how often you are getting infections. It may not be lupus but another autoimmune disease. Hope you feel better soon.