Postpartum mastitis occurs sporadically in nursing mothers, usually with symptom onset after discharge from the hospital. Staphylococcus aureus is usually the causative agent. Women nursing for the first time and those with difficulty breastfeeding appear to be at greatest risk. Rarely, inflammatory carcinoma of the breast can be mistaken for puerperal mastitis (see also Chapter 17-05). Unfortunately, strategies aimed at preventing mastitis in breastfeeding women have been unsuccessful.
Mastitis frequently begins within 3 months after delivery and may start with an engorged breast and a sore or fissured nipple. Cellulitis is typically unilateral with the affected area of breast being red, tender, and warm (see eFigure 17–7). Fever and chills are common complaints as well. Treatment consists of antibiotics effective against penicillin-resistant staphylococci (dicloxacillin 500 mg orally every 6 hours or a cephalosporin for 10–14 days) and regular emptying of the breast by nursing or by using a mechanical suction device. Although nursing of the infected breast is safe for the infant, local inflammation of the nipple may complicate latching. Failure to respond to usual antibiotics within 3 days may represent an organizing abscess or infection with a resistant organism. When the causative organism is methicillin-resistant S aureus (MRSA), the risk for abscess formation is increased when compared with infection caused by nonresistant staphylococcal species. If an abscess is suspected, ultrasound of the breast can help confirm the diagnosis. In these cases, aspiration or surgical evacuation is usually required. Changing antibiotics based on culture sensitivity (to vancomycin or trimethoprim-sulfamethoxazole, for example) is useful, especially if the clinical course is not improving appropriately.
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