Mastitis Organism-Specific Therapy 

Organism-specific regimens for mastitis are provided below, including those for Staphylococcus aureus, coagulase-negative staphylococci, staphylococci, streptococci, and Peptostreptococcus.

Methicillin-sensitive S aureus or coagulase-negative staphylococci

See the list below:

• Dicloxacillin 500 mg QID for 10-14 days or
• Cephalexin 500 mg PO QID for 10-14 days or
• Amoxicillin-clavulanate 500 mg/125 mg PO TID or 875 mg/125 mg PO BID for 10-14 days or
• Clindamycin 600 mg IV q8h or 300 mg PO TID for 10-14 days or
• Trimethoprim-sulfamethoxazole 1 DS tablet PO BID for 10-14 days (caution if nursing preterm infant or child with known or suspected glucose-6-phosphate dehydrogenase [G6PD] deficiency) or
• Nafcillin 2 g IV q4h or
• Oxacillin 2 g IV q4h or

​If beta-lactam allergy:

• Doxycycline 100 mg PO BID for 10-14 days (pregnancy Category D and secreted in breast milk; do not use in pregnancy or if breastfeeding) or
• Clarithromycin 500 mg PO BID for 10-14 days or
• Vancomycin 1 g IV q12h

When clinical improvement is apparent, transition the patient from IV to oral antibiotics for completion of a 10- to 14-day course. ^{[1, 2, 3]}

Methicillin-resistant S aureus or coagulase-negative staphylococci

See the list below:

• TMP-SMZ 160 mg/800 mg 1 DS tablet BID for 10-14 days or
• Clindamycin 600 mg IV q8h or 300 mg PO TID for 10-14 days or
• Doxycycline 100 mg PO BID for 10-14 days (pregnancy Category D and secreted in breast milk; do not use in pregnancy or if breastfeeding) or
• Vancomycin 1 g IV q12h for 10-14 days or

For rare strains or refractory cases:

• Linezolid 600 mg PO/IV q12h for 10-14 days (pregnancy category C; unknown if secreted in breast milk) or
• Tigecycline 100-mg IV infusion, then 50-mg IV infusion q12h for 5-14 days​ (pregnancy Category D and unknown if secreted in breast milk; do not use in pregnancy or if breastfeeding) or
• Daptomycin 4 mg/kg IV infusion q24h for 7-14 days (pregnancy category B; secreted in breast milk but poorly bioavailable orally; use caution if breastfeeding) or

​Emerging treatment options:

The following drugs have been approved by the FDA for treatment of soft-tissue infections but have not yet been assessed specifically for efficacy in treating breast infections.

• Ceftaroline 600 mg IV q12h; infuse over 5-60 minutes for 5-14 days (approved to treat MRSA infections; pregnancy Category B, unknown if secreted in breast milk) or
• Dalbavancin: (1) 1-dose regimen of 1500 mg IV or (2) 2-dose regimen of 1000 mg IV followed 1 week later by 500 mg IV; infuse IV over 30 minutes (pregnancy category C, unknown if secreted in breast milk) or
• Oritavancin: 1-dose regimen of 1200 mg dose IV infusion over 3 hours. (pregnancy category C, unknown if secreted in breast milk)

When clinical improvement is apparent using ceftaroline, transition the patient from IV to oral antibiotics for completion of a 10- to 14-day course. ^{[1, 2, 3, 4, 5]} When using dalbavancin or oritavancin, additional antibiotics are not required except as indicated for failure of clinical resolution.

Streptococci or Peptostreptococcus

See the list below:

• Dicloxacillin 500 mg QID for 10-14 days or
• Cephalexin 500 mg PO QID for 10-14 days or
• Amoxicillin-clavulanate 500 mg PO TID for 10-14 days or
• Clindamycin 600 mg IV q8h or 300 mg PO TID for 10-14 days ^{[1, 2, 3]}

Special considerations

See the list below:

• Milk culture is not specific; 1 mL of normal breast milk may contain >1000 colonies of skin flora
• Milk stasis (as with skipped or incomplete feedings) is a major risk factor for mastitis