Acute mastitis - Infections of the breast

Infections of the breast

Acute mastitis

Definition

Acute bacterial inflammation of the breast is related to lactation in most cases.

Aetiology/pathophysiology

Breast-feeding predisposes to infection by the development of cracks and fissures in the nipple and areola. The infectious agents are most commonly Staph. aureus; other causes include Staph. epidermidis and Strep. pyogenes.

Periductal non-lactating mastitis is associated with smoking in 90%. It has been suggested that smoking may damage the subareolar ducts, predisposing to infection. Peripheral non-lactating mastitis is un-common, but is associated with diabetes, rheumatoid arthritis, steroid treatment and trauma. Infections include Bacteroides, Staph. aureus, Enterococci and anaerobic Streptococci.

Clinical features

Patients present with painful tender enlargement of the breast, often with a history of a cracked nipple. If left untreated an abscess may form after a few days.

Investigations

Swab any pus and send breast milk (where appropriate) for culture and sensitivities.

Management

In lactating mastitis, flucloxacillin is usually sufficient. Breast-feeding should be encouraged as this aids drainage of the affected segment of the breast. There is no evidence of harm to the baby. If pain prevents breast-feeding, the baby should be fed from the non-infected breast and expression of milk used to drain the affected breast.

In non-lactating mastitis, co-amoxiclav is used, with a combination of erythromycin and metronidazole in those who are penicillin-sensitive.

Surgical drainage is rarely required but may be needed once an abscess has formed. An alternative is daily ultrasound-guided aspiration with antibiotics until the infection has resolved.