Three weeks postpartum, a lactating woman develops fever with a unilateral, erythematous, exquisitely tender and fluctuant swelling in the upper outer quadrant of the left breast. Aspiration yields frank pus. The most likely causative organism is:

• A Streptococcus agalactiae
• B Staphylococcus aureus ✓
• C Escherichia coli
• D Candida albicans

Explanation

Lactational mastitis and breast abscess are caused overwhelmingly by Staphylococcus aureus entering through nipple cracks. Management includes drainage, flucloxacillin or equivalent antistaphylococcal therapy, and continuation of breastfeeding or expression, which aids resolution. Streptococcal mastitis occurs but is uncommon, Candida causes superficial nipple pain with radiating burning rather than a fluctuant abscess, and coliforms are not typical of lactational breast infection.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.