Mastitis Organism-Specific Therapy 

Updated: Feb 27, 2018
  • Author: Andrew C Miller, MD; Chief Editor: Thomas E Herchline, MD  more...
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Specific Organisms and Therapeutic Regimens

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

Routine cases:

  • Dicloxacillin 500 mg QID for 10-14 days or
  • Nafcillin 2 g IV q4h for 10-14 days; infuse over 30-60 minutes or
  • Oxacillin 2 g IV q4h for 10-14 days; infuse over 30 minutes or
  • Amoxicillin-clavulanate 875 mg/125 mg PO BID for 10-14 days or
  • Cephalexin 500 mg PO QID for 10-14 days or
  • Clindamycin 600 mg IV q8h infuse over 10-60 minutes (max 30 mg/min) 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)

If beta-lactam allergy:

  • Doxycycline 100 mg PO BID for 10-14 days (pregnancy Category D, secreted in breast milk; do not use in pregnancy or if breastfeeding ) or
  • Ciprofloxacin 500 mg PO BID for 10-14 days (pregnancy Category C, secreted in breast milk, use caution if breastfeeding ) or
  • Clarithromycin 500 mg PO BID for 10-14 days or
  • Vancomycin 1 g IV q12h, target trough levels of 10-15 mcg/mL (MSSA) or 15-20 mcg/mL (MRSA); infusion not to exceed 1 g/hour

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, 4, 5]

Methicillin-resistant S aureus or coagulase-negative staphylococci

Initial or routine cases:

  • Trimethoprim-sulfamethoxazole 160 mg/800 mg 1 DS tablet BID for 10-14 days or
  • Clindamycin 600 mg IV q8h infuse over 10-60 minutes (max 30 mg/min) or 300 mg PO TID for 10-14 days or
  • Doxycycline 100 mg PO BID for 10-14 days (pregnancy Category D, secreted in breast milk; do not use in pregnancy or if breastfeeding ) or
  • Vancomycin 1 g IV q12h for 10-14 days

For rare strains or refractory cases:

  • L inezolid 600 mg PO/IV q12h for 10-14 days, infuse over 30-120 minutes (pregnancy category C; secreted in breast milk, caution if used while breastfeeding ) or
  • T igecycline 100-mg IV infusion, then 50-mg IV infusion q12h for 5-14 days; infuse over 30-60 minutes​ (pregnancy Category D, suspected to be secreted in breast milk; do not use in pregnancy or if breastfeeding ) or
  • Daptomycin 4 mg/kg IV infusion q24h for 7-14 days; infuse over 30 minutes (pregnancy category B; secreted in breast milk in low concentrations, although it has poor oral bioavailability; use caution if breastfeeding)

Streptococci or peptostreptococci

Routine:

​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) or
  • Delafloxacin 450 mg PO q12h for 10-14 days or 300 mg IV q12h for 10-14 days; infuse over 60 minutes (no pregnancy classification, unknown if secreted in breast milk, use caution if pregnant or breastfeeding ) [6, 7]

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, 8, 9] When using dalbavancin or oritavancin, additional antibiotics are not required except as indicated for failure of clinical resolution.

Fungal mastitis

Fungal mastitis should be suspected when pain is disproportional to clinical findings. Pain is often described as “shooting from nipple through the breast to the chest wall.” Concurrent yeast infections, such as oral thrush or diaper dermatitis, are common. Evidence regarding treatment is conflicting. [7]

Mild infections:

  • Nystatin topical applied to affected area q8-12hr for 2 weeks (pregnancy category B, no lactation information) or
  • Miconazole topical applied to affected area BID for 2 weeks (pregnancy category C, no lactation information) or
  • Ketoconazole topical applied to affected area once daily for 2 weeks (pregnancy category C, no lactation information)

Moderate-to-severe infections:

  • Fluconazole 400 mg IV/PO (initial dose), followed by 200 mg daily, for a minimum of 10 days. Single large doses are ineffective. Infants are not adequately treated with the amount of fluconazole that is passed via breast milk and therefore should be treated independently with 6-12 mg/kg initial dose, followed by 3-6 mg/kg/day for a minimum of 10 days.

Recurrent mastitis

Consider the following:

  • Rule out abscess with ultrasonography.
  • Consider choosing an antibiotic to cover (MRSA). [1]
  • If an abscess develops, consider irrigation and debridement along with IV antibiotics.

Special considerations

If lactating:

  • 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