Arly: From Ruth Lawrence's Breastfeeding: A guide for the medical profession, 4th edition, 1994, p. 261: "The common organisms are Staphylococcus aureus, Escherichia coli, and (rarely) Streptococcus." There is no mention of Bacteroides, although probably a number of rarer organisms may be isolated at times. Hope this helps. Alicia. [log in to unmask]