I don't believe Candida becomes resistant to Pau D'arco or at the very least not as quickly or as much as it does other herbs. This may be partly in due to its effectiveness as a tea taken daily over a period of time, as opposed to some other herbal therapies which try to bombard yeast but backfire quickly by having a resistance build up.
As well Pau D'arco is just such a good overall herb that everyone should really drink it regularly. One of the best overall anti-cancer herbs amongst other things. You can find it under the name Taheebo as well and try to buy the bulk organic form, thankfully its also very in-expensive.
I've drank it on and off for the last 5 years or so, and I definitely have less congestion and less candida related symptoms in general when I drink it regularly (Although Candida doesn't appear to be a major issue for me at this point)