The mechanism of breast infection is most likely one in which the infant acquires the pathogenic staphylococcus either in the hospital or home environment and transmits it to the breast upon suckling. Under favorable conditions of milk stasis, retrograde invasion of the duct occurs and an inflammatory process is initiated which may progress to abscess formation. Since the average duration of symptoms was 7.7 days before the patients sought medical care, personalized postpartum instruction to nursing mothers seems essential. This would permit earlier awareness of breast abnormality and allow for prompt antibiotic therapy in order to circumvent abscess formation. Infants who exhibit signs of upper respiratory infection should be removed from the breast, isolated (manual emptying of breasts instituted temporarily), and receive proper antibiotic care. In such cases the two conditions apparently necessary for promoting breast infection are present: (a) inability of sick infants to feed well with resultant ineffectual emptying of breasts, thereby promoting stasis and stagnation, and (b) the presence of a pathogenic organism in the upper respiratory tract of the infant.Infants of mothers who display breast infection should be placed in the isolation nursery and given antibiotic treatment. In smaller hospitals, when mastitis appears on the maternity floor, it would be feasible to administer antibiotics prophylactically to all infants in an attempt to prevent cross infection. At Cook County Hospital this practice would be virtually impossible. All normal postpartum patients leave the institution within 48 to 72 hours of delivery, long before signs and symptoms of infection are manifested. Also, the distribution of drugs to infants numbering in excess of 1,200 per month is in itself a prohibitive procedure. The ultimate but drastic measure for prevention of breast infection would be to eliminate all breast feeding during periods of increased breast infection. Breast feeding could be resumed when the infection has been curtailed.This protracted series of augmented numbers of breast infections would indicate that more than an “outbreak” has occurred. It is more plausible that a new norm or standard of bacterial virulence has been established, which is refractory to the more commonly used antibiotics, particularly penicillin.