If it works, you should start to see significant improvement in about 4
days.  If you have seen no improvement in a week, then it probably never
will.

Biaxin XL is a macrolide antibiotic.  These don't have as wide a
coverage as the quinolones.  Last I checked, they aren't very effective
on S. aureus infections of the sinuses.  Biaxin is easy to tolerate,
except it kills off the bacteria in your gut which can give you some GI
symptoms.  Take acidophilus supplements to compensate for that.

I keep saying that quinolones like Avelox or Levaquin are the "big
guns".  If even they don't work, then it's time to see an ENT.

Remember:  If your sinuses are physically blocked (not just infected),
then no antibiotic will work.  It's no different than lancing a boil or
having an abscessed tooth extracted--you have to physically drain the
infection.  Only an ENT can determine if that is the case.

I would try the Biaxin.  As Steven said, if you don't see improvement
in 4-5 days then it probably isn't going to work, but since you have
had it so long, I would give it at least a week.  I think you said that
you possibly had a tendon problem with Levaquin so I wouldn't try
another quinolone just yet, although I and others have had various
reactions to Levaquin and not other quinolones so Cipro or Avelox may
still be an option.  Actually, doxycycline is being used more freqently
now and has a broad range of coverage.  An allergist I saw at Mayo
Clinic who first suggested I had chronic sinusitis gave what I thought
was good advice.  You should stay on the antibiotic until you have had
at least 5 good days.  That's not to say you should stop it sooner than
it is prescribed. If antibiotics don't work, then you need to see an
ENT.  I also agree with Steven, that if there is blockage then nothing
is going to work. That became my experience. You might also consider at
that point a fungal cause.  If at all possible, sse if you can get
cultures.

Kathyw