Just thinking out loud...
I just started my daughter (3yo) on some Cipro (5%) antibiotics for an UTI. Last night I read the medicine handout which says that I need to avoid giving her a multivitamin, or any product that contains calcium, iron, and/or magnesium (for 2 hours before dosage and 6 hours after--like all the time?!) because **it interferes with the antibiotics ability to work**. (I interpret that to mean it interferes with absorption in the intestines?)
Now, formula is all iron and multivitamin fortified... Baby food and cereals are also commonly fortified. Not sure if the handout is also recommending that my daughter avoid naturally high calcium/iron foods or if it just means man-made supplements...? (I guess I'll have to make another paranoid call to the pharmacy.)
It sounds like re-infection is a possible scenario in your situation. However, since your daughter's infection keeps reoccurring, you might want to investigate whether her diet is interfering with the medicine or her body's ability to absorb it.
Best of luck with it!
Post-Edit:
I found this, with seems to say that dairy foods are also guilty of interfering with absorption.
http://www.drug3k.com/drug/ciprofloxacin-Hcl-13768.htm
- Take Ciprofloxacin Hcl 2 hours before or 6 hours after taking any products containing magnesium, aluminum, or calcium. (Examples include quinapril, didanosine, vitamins/minerals, and antacids).
- Dairy products (e.g., milk, yogurt), calcium-enriched juice, sucralfate, bismuth subsalicylate, iron, and zinc are also included.