I don't think zithromax will cut it when it comes to lyme and bartonella. I highly recommend Biaxin. IV zithromax is good but the oral zith will give you minimal results.
I recommend the following combo if you can tolerate it.
Biaxin, Bactrim, Doxycycline
or
Biaxin, Bactrim, Tetracycline
or
Roxithromycin, Bactrim, Tetracycline(my favorite)