You don't need documentation.  Only common sense.  Mastitis is almost
always caused by staphylococcus aureus.  Almost all staphylococcus
aureus is resistant to amoxycillin (in most areas).  Therefore why on
earth would someone prescribe amoxycillin for mastitis?  It is like
prescribing antibiotics for a viral infection (which is done alot
too).  You don't need documentation.

My approach to mastitis.  If the mother has had symptoms for less than
24 hours (arbitrary on my part), I will give her a script for
cephalexin 500 mg qid, but ask her not to start immediately.  If her
symptoms (pain, area of hardness, fever) are getting worse over 8-12
hours (also arbitrary), then start the cephalexin.  If, in 24 hours,
there is no worsening, but no improvement, then start.  I find that
easily 50% of women are actually improving by 24 hours, *without* the
antibiotics, and then don't need to start.  The symptoms are not gone,
but they are lessening.

So why amoxycillin?  Well if 50% get better, then it will look as if
amoxycillin has worked.  If, in addition, every blocked duct is
treated as mastitis, as many physicians do, it will look as if the
amoxycillin worked.  Just like giving amoxycillin for a cold.  Seems
to work, doesn't it?

Jack Newman, MD, FRCPC