Sometimes half doses of antibiotics are given to prevent an
infection that keeps comming back (like in chronic
bronchitis or urinary tract infections). If you are treating
an active infection - which is what I think you would have
to call it here - full doses should be used and it is really
just duration that is in question with long courses not
uncommon for things like prostate infections and sinusitis.

There have been studies using doxycycline, Baiaxin,
Zithromax, and others for chronic chlamydia and mycoplasma
infections. The generally have run for several months at a
time and the results for erythromycin and doxycyline have
been disappointing (despite supposedly covering the
appropriate organisms). Biaxin has shown some success but
not quite as much as Zithromax. The correlates well with
anecdotal reprots that say Biaxin can work but usually takes
longer.

The regimen that seems tohave the most data and the most
popularity is to that 500mg of Zithromax (azithromycin)
daily for three days as a loading dose then 750 mg weekly
for a total of 12 weeks. It works out to 39 250 mg tablets.

Biaxin has a much shorter half life than Zithromax so it
must be taken twice daily unless you are taking the
sustained release tablet or have kidney problems - usually
250-500mg twice a day (most commonly 500mg).