Robin,
You all were wise to culture and to change scripts pursuing the line of
reasoning revealed by the cultures.  If the meds haven't altered anything
(only slightly reduced sx), consider an ultrasound to rule out abscess or
galactocele.  If a galactocele formed early on and is blocking drainage in
that lobe, you may be able to minimize engorgement- related inflammation
with cold, pumping, rest, etc. but the minute mom gets tired and her immune
response is over-whelmed, she'll have a problem. If it is a galactocele, it
could be defined and aspirated or excised.  The problem is probably mostly
inflammatory which is why meds aren't totally clearing it. Someone posted
recently that antibiotics do have some anti-inflammatory action which is why
they seem to help even in non-infectious mastitis.

 If its not a blockage, there is a management issue (over-supply?)  Maybe
there is a baby who has a sucking or swallowing issue or oral anatomy issue
which prevents good drainage of the whole breast. Another angle: The surgeon
I work with says that ductal yeast infection can produce chronic plugged
ducts. From what you describe, I'm leaning toward the galactocele theory.
Remember:  you can have abscess without febrile sx.  Read Thomsen's work on
mastitis:  inflammatory mastitis has the same sx as infectious only without
the fever and with lower leukocyte cts.

Barbara Wilson-Clay, BSE, IBCLC
priv. pract Austin, Tx
Owner LACTNEWS On-Line:  http://moontower.com/bwc/lactnews.html