Diagnosis

Common causative organism

Management steps

1. Confirm diagnosis / assess extent - clinical exam for fluctuance; ultrasound of the breast is useful to confirm an abscess (vs. inflammatory mastitis alone) and to guide drainage.
2. Drain the abscess - this is the key step once pus has formed (antibiotics alone won't resolve a true abscess):
   • Ultrasound-guided needle aspiration is now favored as first-line for most abscesses - repeated aspiration every 1-3 days if fluid reaccumulates. A recent meta-analysis (Zhou et al., 2023, PMID: 37350731) found needle aspiration gives comparable cure rates to incision and drainage with less scarring, less pain, and shorter healing time, particularly for smaller/uncomplicated abscesses.
   • Incision and drainage (I&D) is reserved for large, multiloculated abscesses, thick pus that won't aspirate, overlying skin necrosis, or failure of repeated aspiration. Counter-incision with a dependent drain may be used for loculated collections - Bailey & Love's Short Practice of Surgery; Pye's Surgical Handicraft.
   • Send pus for Gram stain and culture/sensitivity to guide antibiotic choice, especially given rising MRSA rates.
3. Antibiotics - empirical anti-staphylococcal coverage while awaiting culture:
   • Dicloxacillin or flucloxacillin (first line for non-MRSA)
   • Cephalexin as an alternative
   • Clindamycin or trimethoprim-sulfamethoxazole if MRSA is suspected/confirmed (choose agents compatible with breastfeeding)
   • Typical duration 10-14 days
4. Supportive care
   • NSAIDs/analgesics for pain and fever
   • Warm compresses before feeding/expressing
   • Adequate hydration and rest
   • Ensure frequent, effective emptying of the breast (feeding, hand expression, or pump)
5. Follow-up - reassess in 48-72 hours; if not improving, re-image and consider repeat aspiration, broader antibiotic coverage, or ruling out inflammatory breast carcinoma if the mass persists after resolution of infection (important in atypical or non-resolving cases).

Should breastfeeding continue?

• Continued milk drainage helps resolve the infection and prevents further milk stasis, which would worsen mastitis/abscess.
• It does not harm the infant - S. aureus in milk is not a contraindication to feeding.
• If direct latching on the affected breast is too painful or the incision site interferes with feeding, express milk mechanically from that side until comfortable, while continuing to feed from the unaffected breast.
• Antibiotics selected should be breastfeeding-compatible (the ones listed above are standard safe choices).
• Abrupt cessation of feeding/pumping risks engorgement and abscess recurrence.