Tea bags contain tannic acid.  If anything, acid inhibits the growth of
yeast.  I don't see why they would contribute to yeast, but they have been
shown not to reduce nipple soreness (at least not compared to L_nsin_h
anhydrous ultra pure lanolin).  If the bags contain fungus, from poor
storage, then there might be a problem.  IMNHO, the hospital staff should be
recommending techniques that are more in line with current practice:
topical anhydrous ultra pure medical grade lanolin, ibuprofen, ice flowers
(crushed ice in a towel), etc.