aetiology

Last reviewed 01/2023

There are two main causes of mastitis

• milk stasis
  • caused by inadequate emptying of the breast
  • situations which predispose to milk stasis are:
    • soon after delivery when the breasts are engorged
    • when the infant does not remove the produced milk
    • an overabundant milk supply
    • lactating for multiple e.g. - twins
    • infection
  • the route of infection is uncertain, organisms may enter the breast tissue through
    • the lactiferous ducts into a lobe
    • through haematogenous spread
    • through the periductal lymphatic system (1)
  • commonest organisms seen in mastitis and breast abscess are
    • Staphylococcus aureus
    • Staph. albus
  • other less frequent infectious organisms causing mastitis are:
    • E. coli
    • Streptococcus (alpha, beta and non- haemolytic)
    • M. tuberculosis
    • Candida and cryptococcus
    • salmonella infections (1)

The following factors have been recognised as predisposing factors for mastitis:

• milk stasis
  • poor positioning and attachment leading to ineffective breast emptyingrestriction of infant feeding - due to feeding schedule, long intervals between feeds or due to missed or short feeds
  • abrupt cessation of breast feeding
  • oversupply of milk
  • engorged breasts
  • blocked milk ducts
  • pressure on the breast - can be due to wearing a tight bra or from a car seat belt
  • stress and fatigue of mother
• nipple trauma

Reference:

• 1. World Health Organization (WHO) 2000. Mastitis: Causes and Management
• 2. Guidelines and Audit Implementation Network (GAIN) 2009. Guidelines on the treatment, management & prevention of mastitis
• 3. Academy of breastfeeding Medicine. Mastitis