Hello Minimouse and welcome,
As well as this site, I think you and your mother would really benefit by looking at http://www.CPn Help.org
, where not only do a lot of people who post both on the antibiotics and regimens sections here post, but also there is much information by various physicians, especially from Charles Stratton at Vanderbilt, who has done most of the research about chlamydia pneumoniae, but others also, including my husband, David Wheldon, who has treated me, and Mike Powell from Sacramento. The home page gives a brief introduction then there are the treatment pages and the physician's pages for starters.
If your mother is to start abx to treat her MS, she really needs to use something which crosses the blood brain barrier, so in CPn Help you will find info about which abx are the most effective. Also on this site, http://www.davidwheldon.co.uk/ms-treatment.html
. Everything here is effective both against CPn and lyme: it was devised to be so. Flagyl comes later in the treatment, at the bactericidal phase. I started it after about three months and took it in pulses of five days at a time, whilst still taking the other abx.
I was diagnosed with aggressive secondary progressive MS two and a half years ago. I am married to someone who was sure that there was an infective cause to MS. He prescribed doxycycline and roxithromycin, which would have to be swapped for azithromycin in the US. Then flagyl after three months. I took all this full-time for a year then swapped to intermittent therapy because I was doing so well. Now I take two weeks every two months or so. My disability rating has gone down from about seven to less than two. In addition I have regained all my mental faculties. I tested diagnostically negative for CPn and totally negative for lyme. Both are very difficult pathogens to unearth, so treatment is often best made empirically.
So take your time and read both sites, then ask some more questions on either place. Do take note of the various supplements recommended as well. This is a very important part of the treatment. You will benefit enormously by taking it all on board.