Description of the condition

Mastitis is an inflammatory condition of the breast, usually associated with lactation (WHO 2000). Hence, it is also known as lactational mastitis (Hughes 1989) or puerperal mastitis (Editorial 1976). An estimated 2% to 33% of breastfeeding women develop lactational mastitis (Buescher 2001; Fetherston 1998; Foxman 2002; Jonsson 1994; Kaufmann 1991; Kinlay 1998; Marshall 1975; Riordan 1990; Vogel 1999). Population‐based studies in Australia reported that 15% to 20% of women during the first six months after delivery were affected, while a cohort study of American women reported that 10% of women experienced mastitis during the three months following the birth. Mastitis may recur: a New Zealand study of 350 lactating mothers showed a 8.5% recurrence rate.

The primary cause of mastitis is milk stasis (Hughes 1989), which may or may not be associated with infection. Mastitis can be caused by ineffective positioning of the baby at the breast, limited feeding (in cases where the mother is introducing formula feeding), or restricted feeding, all of which may result in milk stasis and mastitis. In infective mastitis, Staphylococcus aureus and Staphylococcus albus are the commonest organisms found on laboratory investigation (Novy 1984; Riordan 1990). Escherichia coli (Lawrence 1999) and streptococci are found less frequently (Novy 1984). Delayed, inappropriate or inadequate treatment may result in unnecessary discontinuation of breastfeeding, breast tissue damage, recurrence, and substantial cost (Evans 1995).

Clinical symptoms of mastitis include unilateral breast pain, redness (erythema) and swelling, and may be associated with flu‐like symptoms (fever, chills and aches). Unilateral erythema, oedema and tenderness of the affected breast are usually present on examination. In contrast, engorgement of the breast is normally bilateral and uncomfortable rather than acutely painful; and in cases of breast abscess, a fluctuating, tender and hard breast mass is found with overlying erythema (Bedinghaus 1997; Hager 1992; Ogle 1988). Milk leucocyte count, bacteria colony count and culture may be useful investigations to differentiate infective from non‐infective mastitis (Thomsen 1984).

Description of the intervention

The principles of treating mastitis include supportive counselling and supportive therapy (bed rest, increased fluids), effective milk removal (by encouraging the continuation of breastfeeding and assessing how the baby is feeding; helping the mother to adjust positioning and attachment if necessary; and milk expression), symptomatic treatment (pain medication, use of anti‐inflammatory agents), antibiotic therapy (Walker 1999), probiotic therapy (Jimenez 2008) and other agents such as nisin (Fernandez 2008). Although efficient milk removal is the mainstay of treatment, antibiotics are usually prescribed to cover possible bacterial infections. These include penicillin, dicloxacillin and cephalosporins (Hager 1992; Marchant 2002) for staphylococcal and streptococcal infections; for gram‐negative organisms, cephalexin or amoxicillin may be appropriate (Olsen 1990).

The use of antibiotics in the treatment of mastitis varies worldwide, and researchers have been unable to reach a consensus on whether to prescribe antibiotics for women with lactational mastitis. Osterman 2000 underscored the benefit of prescribing both antibiotic therapy and supportive treatment in the presence of infective agents. They prescribed antibiotics after bacterial cultivation for 61% of participants in a cohort of lactational women with mastitis. The authors argued that since breast milk potentially contained pathogenic bacteria, the majority of the mothers should be treated with antibiotics. However, Kvist 2004 only treated 9% of breast inflammation with antibiotics. A study in Western Australia treated 85% of participants with inflammatory breast symptoms with antibiotics (Kvist 2005).

Matheson 1988 concluded that phenoxymethylpenicillin failed to stop abscess formation in 20% of mothers suffering from mastitis and that the majority of them recovered without antibiotics. Amir 2004a stated that low incidence of abscess formation (0.1% in their study) raised the question as to whether antibiotic therapy is appropriate for all mothers with symptoms of breast inflammation. They reported that only 2.9% (95% confidence interval 1.0 to 6.7) of women who took antibiotics for mastitis developed abscesses.

There has also been argument about the type of antibiotic chosen for breastfeeding women suffering from mastitis. Practice relating to the choice of antibiotic therapy has varied widely. An audit of the management of mastitis in the emergency department of Melbourne Hospital, Australia, showed that the majority of women with mastitis received flucloxacillin (91 women out of 111), a beta‐lactamase stable penicillin closely related to cloxacillin, as recommended by Australian Antibiotic Guideline (1996) (Amir 2004b). Amir reported that, due to adverse hepatic events, dicloxacillin should replace flucloxacillin (Amir 2004b). A prospective study (n = 840) conducted in the US between 1994 and1998 reported that 86% of women with mastitis received antibiotics, most of whom were on cephalexin (46%). The rest received amoxicillin (7%), ampicillin (7%) and amdinocillin clavulanate (7%). No cultures were performed because of cost restrictions (Foxman 2002). Another recent publication (Eglash 2006) reported a chart review of 64 women with lactational mastitis presenting to a lactation specialist between 1997 and 2002; these women received routine antibiotic therapy at the time inclusive of cephalexin, dicloxacillin, erythromycin, amoxicillin and clindamycin. The choice of antibiotics was based on the mother's and her baby's records of allergies and intolerances; mother's preference regarding the frequency of antibiotic administration; bacterial culture and sensitivities, and medication cost.

Why it is important to do this review

There is little consensus on who should be prescribed antibiotics, the most appropriate antibiotic to use, the best time to begin treatment and how long the treatment should continue. Most studies have focused on the effectiveness of emptying the breast and the timing of treatment, rather than on the type of antibiotics used (Crepinsek 2010; Devereux 1970; Kinlay 1998; Thomsen 1984). Use of laboratory investigation before antibiotic therapy is not consistent, and type of antibiotic chosen depends on physician choice rather than scientific proof. There is also little information on the cost‐effectiveness of different therapies.