Neonatal mastitis.

Forty-one cases of neonatal mastitis seen at Children's Hospital, Boston since 1947 have been analyzed and the literature since 1950 reviewed. All 41, like those in the literature, occurred in full-term infants 1-5 weeks of age, with a sex ratio of 2:1 (females:males). Bilaterality was rare (3) cases in this series, one in the literature review) and systemic spread or extramammary foci even rarer. The incidence has changed little in the past 35 years except for the larger number of cases in the 1950s. In the present series, all but a few cases have been caused by Staphylococcus aureus, and gram-negative enteric bacilli have not been seen. Therapy is surgical incision and drainage when fluctuance is present, but early treatment with appropriate intravenous antibiotics has apparently obviated the need for surgery in many recent cases. The prognosis for cure of the infection is excellent.