Very interesting story.
Miconazole and gentian violet are antifungals that have antibacterial
properties; I'm not aware of antibiotics having antifungal properties.
However, antibiotics do have antiinflammatory properties (which is why
mastitis symptoms may settle so quickly on antibiotics even if the
antibiotic is inappropriate).
How often do damaged nipples harbour bacteria such as Staph aureus? My
thrush study involved swabbing nipples, and I grew a lot of Staph: if the
fissure looks a little yellow it grew Staph for sure. I didn't treat the
Staph (as I wouldn't have treated clinically, and many of the women had just
been taking anti-staph antibiotics for mastitis), but treated them for
thrush and most got better. I think the staph is a contaminant that grows
whenever the skin is broken down. The study has just been published in
Gynecologic and Obstetric Investigation, 1996; 41: 30-34.
More work is definitely needed to work out the relationship between
bacterial nipple infections and nipple pain.
I don't know the answers to this case: but I just wonder  - is the story
over yet?

Lisa Amir
GP / LC in Melbourne, Australia