A 26-year-old mother on day 5 postpartum develops unilateral breast abscess confirmed on ultrasound. She wishes to continue breastfeeding from the affected breast. What is the drug of choice for antibiotic therapy?

Explanation

## Antibiotic Management of Postpartum Breast Abscess **Key Point:** Flucloxacillin (or cephalexin as alternative) is the drug of choice for postpartum breast abscess because it targets Staphylococcus aureus (the most common pathogen), achieves excellent breast tissue penetration, and is safe during breastfeeding. ### Pathogen Epidemiology in Postpartum Mastitis/Abscess | Pathogen | Frequency | Notes | |----------|-----------|-------| | **Staphylococcus aureus** | 70–80% | Most common; includes MSSA and MRSA | | Streptococcus agalactiae | 10–15% | Group B Strep | | Enterobacteriaceae | 5–10% | E. coli, Klebsiella | | Anaerobes | Rare | Usually polymicrobial | ### First-Line Antibiotic Regimens | Drug | Dose | Duration | Rationale | |------|------|----------|----------| | **Flucloxacillin** | 500 mg QID | 10–14 days | β-lactamase stable; excellent S. aureus coverage; safe in lactation | | **Cephalexin** | 500 mg QID | 10–14 days | Alternative if penicillin allergy (non-severe); good breast penetration | | Clindamycin | 300–450 mg TID | 10–14 days | Reserved for MRSA or severe allergy; less ideal first-line | | TMP-SMX | 160/800 mg BD | 10–14 days | Older agent; less preferred; higher infant exposure | **Clinical Pearl:** Breast abscess in lactating women requires both antibiotics AND drainage (needle aspiration or surgical incision). Antibiotics alone are insufficient. Continued breastfeeding or expression from the affected breast is encouraged to prevent reaccumulation. **High-Yield:** Flucloxacillin is the preferred agent because: 1. Covers MSSA (most common cause) 2. β-lactamase stable (resists staphylococcal β-lactamase) 3. Achieves high concentrations in breast tissue and milk 4. Minimal infant exposure; safe during lactation 5. Recommended by RCOG, NICE, and WHO guidelines **Warning:** Do NOT use erythromycin as monotherapy — it has poor activity against S. aureus and is outdated for this indication. TMP-SMX achieves higher milk levels and may cause kernicterus in neonates with G6PD deficiency. **Mnemonic:** **FLUC** = **F**lucloxacillin is **L**actation-safe, **U**seful against **C**occi (Staph aureus). [cite:RCOG Green-top Guideline 64: Mastitis and Breast Abscess; NICE Guideline NG121: Postnatal Care]