breast abscess

1st tests to order

breast ultrasound diagnostic needle aspiration drainage cytology of nipple discharge or sample from fine-needle aspiration milk, aspirate, discharge, or biopsy tissue for culture and sensitivity histopathological examination of biopsy tissue

Tests to consider

pregnancy test blood culture and sensitivity mammogram milk for leukocyte counts and bacteria quantification culture from swab/aspirate from infant's and mother's oral cavity and nasopharynx FBC tuberculin skin test (PPD)

Treatment details

Acute

lactational mastitis

symptoms not severe or not prolonged: no systemic signs and negative culture o effective milk removal and supportive care

symptoms severe or prolonged or systemic signs: MRSA excluded by culture or not prevalent in area and no penicillin allergy

o oral anti-staphylococcal penicillino effective milk removal and supportive careo antifungal therapy for mother and infanto vancomycin or other antibiotic with activity against MRSA and re-assess diagnosiso effective milk removal and supportive careo antifungal therapy for mother and infant

symptoms severe or prolonged or systemic signs: MRSA confirmed by culture or prevalent in area, or penicillin allergy

o non-beta-lactam antibiotico effective milk removal and supportive careo antifungal therapy for mother and infanto vancomycin (if not already used first-line) or other antibiotic with activity against MRSA and re-

assess diagnosiso effective milk removal and supportive careo antifungal therapy for mother and infant

non-lactational mastitis in adults and adolescents

adults: MRSA excluded by culture or not prevalent in area and no penicillin allergy o oral anti-staphylococcal penicillin or topical therapy plus supportive care

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o switch to appropriate therapy for underlying cause if neededo vancomycin or other antibiotic with activity against MRSA and re-assess diagnosiso switch to appropriate therapy for underlying cause if needed

adults: MRSA confirmed by culture or prevalent in area or penicillin allergy o non-beta-lactam antibiotic plus supportive careo switch to appropriate therapy for underlying cause if neededo vancomycin (if not already used first-line) or other antibiotic with activity against MRSA and re-

assess diagnosiso switch to appropriate therapy for underlying cause if needed

adolescents (age 12-17 years): MRSA excluded by culture or not prevalent in area and no penicillin allergy

o oral anti-staphylococcal penicillin plus supportive careo re-assess diagnosis and treatment

adolescents (age 12-17 years): MRSA confirmed by culture or prevalent in area or penicillin allergy o non-beta-lactam antibiotic plus supportive careo re-assess diagnosis and treatment

mastitis in neonates, infants, and children (<12 years)

MRSA excluded by culture or not prevalent in area and no penicillin allergy o intravenous anti-staphylococcal penicillin or first-generation cephalosporin plus supportive careo re-assess diagnosis and treatment

MRSA confirmed by culture or prevalent in area or penicillin allergy o non-beta-lactam antibiotic plus supportive careo re-assess diagnosis and treatment

breast abscess

adult: MRSA excluded by culture or not prevalent in area and no penicillin allergy o intravenous or oral antibiotic with activity against methicillin-sensitive staphylococci plus

supportive careo re-assess diagnosis and treatmento surgical intervention

adult: MRSA confirmed by culture or prevalent in area or penicillin allergy o non-beta-lactam antibiotic plus supportive careo re-assess diagnosis and treatmento surgical intervention

neonate, infant, or child: MRSA excluded by culture or not prevalent in area and no penicillin allergy o antibiotic with activity against methicillin-sensitive staphylococci plus supportive careo re-assess diagnosis and treatmento surgical intervention

neonate, infant, or child: MRSA confirmed by culture or prevalent in area or penicillin allergy o non-beta-lactam antibiotic plus supportive careo re-assess diagnosis and treatmento surgical intervention

Ongoing

breast abscess post acute intervention

consideration of further surgical intervention

recurrence of mastitis and/or breast abscess

re-assessment and treatme’nt

Definition

Mastitis is inflammation of the breast with or without infection. Mastitis with infection may be lactational (puerperal) or non-lactational (e.g., duct ectasia). Non-infectious mastitis includes idiopathic granulomatous inflammation and other inflammatory conditions (e.g., foreign body reaction). A breast abscess is a localised area of infection with a walled-off collection of pus. It may or may not be associated with mastitis.

Epidemiology

The global prevalence of mastitis in lactating women is approximately 1% to 10% but may be higher. [1] [2] [3] [4] [5] Duct ectasia (peri-ductal mastitis or dilated ducts associated with inflammation) occurs in 5% to 9% of non-lactating women. Breast abscess develops in 3% to 11% of women with mastitis with a reported incidence of 0.1% to 3% in breastfeeding women. [4] [6] [7] Approximately 50% of infants with neonatal mastitis will develop a breast abscess. [8] Tubercular mastitis is rare, even in TB-endemic countries, with a reported incidence between 0.1% and 3%. [9] Mammary fistula occurs in 1% to 2% of women. [6] Idiopathic granulomatous mastitis is a very rare breast condition. [10]

Aetiology

Mastitis may occur with or without infection. Infectious mastitis and breast abscess are usually caused by bacteria colonising the skin. Cases due to Staphylococcus aureus are by far the most common, followed by those due to coagulase-negative staphylococci. The majority of S aureus isolates are now resistant to methicillin. [11] [12]

Breast infections may sometimes (up to 40% of abscesses) be polymicrobial, with isolation of aerobes (Staphylococcus, Streptococcus, Enterobacteriaceae, Corynebacterium, Escherichia coli, and Pseudomonas) as well as anaerobes (Peptostreptococcus, Propionibacterium, Bacteroides, Lactobacillus, Eubacterium, Clostridium, Fusobacterium, and Veillonella). [8] [11] [13] [14] [15] [16] Anaerobes are sometimes isolated in abscesses and chronic recurrent cases. A study of primary and recurrent breast

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abscesses showed that smokers were more likely to have anaerobes recovered (isolated in 15% of patients). [17]

More unusual pathogens may include Bartonella henselae (the agent of cat scratch disease), mycobacteria (TB and atypical mycobacteria), Actinomyces, Brucella, fungi (Candida and Cryptococcus), parasites, and maggot infestation. Unusual breast infections may be the initial presentation of HIV infection. [18] [19]

Non-infectious mastitis may result from underlying duct ectasia (peri-ductal mastitis or plasma cell mastitis) and infrequently foreign material (e.g., nipple piercing, breast implant, or silicone). [20] [21] Granulomatous (lobular) mastitis is a benign disease of unknown aetiology. [10]

Pathophysiology

In lactational mastitis, milk stasis or milk overproduction, coupled with infection from bacteria entering the breast via a traumatised nipple (e.g., cracked or fissured) and/or from the infant's mouth, can lead to mastitis. [5] View image Transient breast enlargement from maternal hormones in neonates makes them vulnerable to mastitis.

In duct ectasia (dilated ducts associated with inflammation), the mammary duct-associated inflammatory disease sequence involves squamous metaplasia of lactiferous ducts. This causes blockage (obstructive mastopathy) with peri-ductal inflammation and possible duct rupture. [6] View image Inflamed ducts are prone to bacterial infection. [22] [23] Left untreated, mastitis may cause tissue destruction resulting in an abscess.

A lactational abscess tends to be located in the peripheral breast. Abscesses unrelated to breastfeeding are more commonly sub-areolar in location. An abscess may also occur without apparent preceding mastitis. Rupture of an abscess can lead to a draining sinus with a resulting fistula. In tubercular mastitis, mycobacterial bacilli can enter the breast from:

Direct inoculation (primary infection) via a nipple abrasion Distant portals (secondary infection), such as lymphatic spread, haematogenous (miliary)

dissemination, or contiguous spread (e.g., empyema necessitans).

TB of the breast may present with a nodular, diffuse, or sclerosing reaction. The most common presentation is a painless lump with or without a sinus tract. Most cases of tuberculous mastitis are secondary, and infection occurs via contiguous spread from lymphatics (most commonly axillary, followed by cervical or mediastinal nodes) or less commonly from the pleura or chest wall or via the haematogenous route. Primary TB of the breast is rare. In some cases tubercular mastitis may be mistaken for breast carcinoma. View image

Necrotising granulomas are the histopathological hallmark of TB infection. In idiopathic granulomatous mastitis, non-necrotising granulom

atous inflammation is centred on lobules that clinically may result in a painless mass. View image

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Classification

Types of mastitis and breast abscess

Lactational mastitis: breast inflammation with or without infection associated with breastfeeding. Non-lactational mastitis: breast inflammation associated with or without infection in the non-

lactating breast. Non-infectious mastitis: breast inflammation due to a non-infectious and/or idiopathic aetiology. Subclinical mastitis: refers to the finding of a raised sodium/potassium ratio and interleukin in milk

without clinical mastitis. [1] Breast abscess: localised breast infection with a walled-off collection of pus.

Primary prevention

Good breastfeeding habits (e.g., emptying breasts fully and proper latching) and proper nipple hygiene may help to minimise the risk of developing lactational mastitis. Sterile equipment and techniques should be used for nipple piercing.

Secondary prevention

Prompt treatment of mastitis will prevent complications such as a breast abscess. Breastfeeding should be encouraged if feasible during lactation. Smoking cessation should also be encouraged to minimise the risk of recurrence. Mastitis may increase the risk of transmission of HIV through breastfeeding. [1] Therefore, if an HIV-positive woman develops mastitis or an abscess, she should avoid breastfeeding from the affected side while the condition persists. [1]

History & examination

Key diagnostic factorshide all

flu-like symptoms, malaise, and myalgia (common)

Patients with mastitis and/or breast abscess may complain of systemic symptoms.

fever (common)




Mastitis may occur with or without a pyrexia >38°C (>100.4°F). Breast abscess may or may not be accompanied by fever.

breast pain (common)

Usually sharp, shooting breast pain, especially with breastfeeding, may indicate mastitis.

decreased milk outflow (common)

Milk stasis may be associated with the development of mastitis.

breast warmth (common)

Inflammatory symptom suggestive of mastitis and a possible underlying abscess. Lactational mastitis tends to involve more peripheral wedge-shaped areas.

breast tenderness (common)

Inflammatory sign suggestive of mastitis and/or abscess. Lactational mastitis tends to involve more peripheral wedge-shaped areas.

breast firmness (common)

Inflammatory symptom suggestive of mastitis and a possible underlying abscess. Lactational mastitis tends to involve more peripheral wedge-shaped areas.

breast swelling (common)

Inflammatory symptom suggestive of mastitis and/or abscess. Lactational mastitis tends to involve more peripheral wedge-shaped areas. Swelling may indicate skin oedema and/or underlying abscess formation. [8]

breast erythema (common)

Inflammatory sign suggestive of mastitis and a possible underlying abscess. View image View image Lactational mastitis tends to involve more peripheral wedge-shaped areas.

breast mass (uncommon)

May occur with a tender area of localised mastitis or breast abscess. A late abscess may result in a fluctuant palpable mass.

fistula (uncommon)

A fistula is usually associated with a draining sinus from an underlying abscess.

Other diagnostic factorshide all

nipple discharge (uncommon)




May occur with or without mastitis. Often associated with duct ectasia (dilated breast duct associated with inflammation). Purulent discharge is usually indicative of infection.

nipple inversion/retraction (uncommon)

Infrequently seen with mastitis.

lymphadenopathy (uncommon)

Tender axillary lymph nodes may occur with ipsilateral breast infection.

extra-mammary skin lesions (uncommon)

Patients with mastitis and/or breast abscess may present with systemic signs including extra-mammary skin lesions.

Risk factorshide all

Strongfemale gender

Breast infection more frequently involves the female breast. Inflammation of the male breast may occur but is unusual.

women 15 to 45 years of age

Breast infection typically affects women 15 to 45 years of age, infants <2 months of age, and adolescent girls. [2] [24] [25]

Women aged >30 years have a higher risk of mastitis, possibly related to milk stasis. [26]

adolescent girls


infants <2 months of age


Transient breast enlargement from maternal hormones in neonates makes them vulnerable to mastitis.

poor breastfeeding technique

Poor breastfeeding positioning, or oral infection, tongue-tie, a skin infection, and nappy rash in the infant may be associated with the development of lactational mastitis.











lactation

Lactational mastitis is more common at 6 to 8 weeks of breastfeeding or at weaning. Mastitis is uncommon during pregnancy itself.

milk stasis

Associated with infectious (lactational) and non-infectious mastitis. May result from inadequate drainage, blocked ducts, milk oversupply, external pressure on the

breast (e.g., tight-fitting bra), infrequent feeding, or rapid weaning. [1]

nipple injury

Nipple cracks and fissures permit bacteria to gain entry into the breast. Injury may occur when an older teething baby bites a nipple or from use of a breast pump that

generates excessive vacuum.

previous mastitis

Women who have had mastitis have an increased rate of recurrence with subsequent births (approximately 12%).

prolonged mastitis (breast abscess)

Prolonged mastitis may be associated with breast abscess formation.

prior breast abscess (breast abscess)

There is a high rate of recurrence with a remote history of prior breast abscesses.

shaving or plucking areola hair

Pulling hair from the areola may cause a Montgomery follicle abscess with potential for more widespread infection.

anatomical breast defect, mammoplasty, or scar

Altered duct structure may interfere with milk flow and predispose to mastitis.

other underlying breast condition

Particularly breast cancer.

nipple piercing

Breast infection may develop up to 52 weeks after piercing in 10% to 20% of cases. [21]

foreign body



Silicone and breast implants may cause mastitis with or without infection. Silicone mastitis may cause a hard, tender, erythematous breast mass.

skin infection

Dermatoses, such as psoriasis or eczema, may cause nipple fissures that result in recurrent mastitis.

Afflicted women are also more likely to harbour Staphylococcus aureus. Maternal skin infections may be linked to neonatal mastitis. In neonates, extra-mammary skin infections may be associated with mastitis. [27]

Staphylococcus aureus carrier

The vast majority of cases of infectious mastitis and breast abscess are caused by S aureus.

immunosuppression

Patients with diabetes or HIV infection, and those on immunosuppression therapy are at risk for developing breast infections. [18]

Diabetes mellitus is strongly associated with breast abscess in non-lactating women. [28]

Weakhospital admission

Epidemic (hospital-acquired) puerperal mastitis should be considered in any patient with signs of breast infection during or after a hospital admission.

breast trauma

Trauma to the breast may infrequently result in inflammation. Domestic violence in such cases should always be considered. A traumatised neonatal breast bud, even from minor manipulation, is highly prone to developing

mastitis.

primiparity

Found to be a risk factor for both mastitis and breast abscess in some studies but not in others. [1]

overabundant milk supply

For example, as may occur with lactation for twins or higher multiples. May predispose to milk stasis. [1]

post-maturity (breast abscess)

Gestational age of 41 weeks or more is associated with an increased risk of breast abscess. [26]

complications of delivery







May increase the risk of lactational mastitis. [1]

maternal fatigue

Stress, sleep deprivation, exhaustion, and returning to work have all been associated with lactational mastitis.

tight clothing

Believed to promote milk stasis. [1]

antifungal nipple cream

Repeat application of antifungal cream for nipple thrush may cause nipple injury and possibly a change in normal flora. [3]

fibrocystic breast disease

May interfere with milk flow.

cigarette smoking

Smoking hinders the breast milk ejection reflex and raises the risk of engorgement and subsequent lactational mastitis.

Smoking is also associated with non-lactational mastitis in young women, as well as primary and recurrent breast abscess. [29] [30]

vaginal manipulation (breast abscess)

Resulting transient bacteraemia is believed to be associated with anaerobic breast abscess formation. [31]

poor nutrition

Thought to predispose to mastitis. Vitamin A deficiency promotes squamous metaplasia, which is thought to cause obstructive

mastopathy. [1]

Diagnostic tests

1st tests to orderhide all

Test Result

breast ultrasound

For an erythematous area, ultrasonography helps to

hypoechoic lesion (abscess); may be well circumscribed, macrolobulated, irregular, or ill








identify an underlying abscess. [32] [33] [34]

Abscesses usually form a hypoechoic lesion. View image

This is the preferred imaging modality in adolescents, and is applicable in neonates with suspected breast infection. [35]

defined with possible septae

diagnostic needle aspiration drainage

A breast abscess can be drained by needle aspiration for therapeutic and diagnostic purposes. View image

Can be directed by ultrasound guidance.

purulent fluid indicates a breast abscess

cytology of nipple discharge or sample from fine-needle aspiration

Nipple discharge and fine-needle aspirate should be sent for cytological evaluation, looking for underlying malignancy in addition to infection.

if present: infection and/or malignancy demonstrated

milk, aspirate, discharge, or biopsy tissue for culture and sensitivity

Milk, aspirates, nipple, or sinus discharge, and biopsy tissue should be sent for bacterial (aerobic and anaerobic) culture and sensitivity.

Fungal and mycobacterial studies may be performed, but usually only if the condition is refractory to antibiotics.

Mycobacteria are usually demonstrable in only 12% to 33% of mammary TB. [9] [42]

positive culture indicates infection

histopathological examination of biopsy tissue

Excised tissue should be sent for histopathological evaluation, especially in refractory and recurrent cases.

Skin-punch biopsy can be undertaken to diagnose inflammatory breast carcinoma.

if present: infection, granulomatous inflammation, or malignancy demonstrated.

Tests to considerhide all

Test Result










pregnancy test

If mastitis develops unexpectedly, such as in an adolescent, a pregnancy test should be considered.

may be positive

blood culture and sensitivity

If systemic infection suspected, should be sent for bacterial (aerobic and anaerobic) culture and sensitivity.

Fungal and mycobacterial studies may be performed, but usually only if the condition is refractory to antibiotics.

Results guide appropriate therapy.

positive culture indicates systemic infection

mammogram

Useful to help identify underlying breast lesions.

Mammographic findings of breast infection and abscess are often non-specific and may mimic cancer. [33] [34] [38] [39] View image

It is usually too painful to perform a mammogram if an abscess is present.

Should be ordered (following resolution of the acute phase) in women >40 years of age and whenever the presentation is complicated or atypical, or malignancy is suspected. [40]

non-specific findings in acute phase; may demonstrate underlying lesion if performed after the acute phase

milk for leukocyte counts and bacteria quantification

Expressed milk or a midstream sample can be sent for leukocyte counts and bacteria quantification. [37]

Although the presence of pathogenic bacteria and/or high bacterial counts (>10^3/mL of milk) indicates mastitis, the predictive value is low. Therefore, the presence of bacteria in milk does not necessarily indicate infection. [1]

leukocytes >10^6/mL milk and bacteria <10^3/mL milk indicates non-infectious mastitis; leukocytes >10^6/mL milk and bacteria >10^3/mL milk indicates infectious mastitis

culture from swab/aspirate from infant's and mother's oral cavity and nasopharynx

For recurrent cases of lactational mastitis, cultures from the infant's and mother's oral cavity and nasopharynx are submitted to determine their

may be positive for Staphylococcus aureus if a carrier









staphylococcal carrier status.

FBC

Indicated for patients who appear toxic or have an abscess, recurrent infection, or treatment failure.

Also indicated in neonates.

normal; leukocytosis with infection; neutropenia with immunosuppression

tuberculin skin test (PPD)

If active TB is suspected or needs to be ruled out.

Microbiological studies and/or biopsy should also be performed.

often positive with active TB

Differential diagnosisCondition Differentiating signs/symptoms Differentiating tests

Breast engorgement

Engorgement usually occurs on the third to fifth post-partum day.

There may be bilateral generalised breast pain, firmness, erythema, warmth, and a mild fever (milk fever), but there is usually no oedema.

Relieved by frequent emptying of the breasts (e.g., breastfeeding).

Usually becomes clinically apparent as breastfeeding continues.

Nipple sensitivity

There is usually no evidence of nipple trauma, features of breast inflammation, or fever.

Nipple vasospasm (Raynaud's phenomenon) may manifest with nipple pain.

Nipple sensitivity with breastfeeding usually subsides once suckling begins, whereas pain from trauma or infection persists or increases.

Usually becomes clinically apparent as breastfeeding continues.

Galactocoele A milk retention cyst may cause a tender palpable breast lump, but

A galactocoele appears on ultrasound as a well-defined lesion with a thin

there are usually no sharp shooting pains and no signs of breast inflammation or systemic illness.

echogenic wall, which may contain coarse calcification. A breast abscess may also be well circumscribed, macrolobulated, irregular, or ill defined with possible septae.

Galactocele aspiration yields non-purulent milk.

Fibrocystic breasts

Painful breast tissue before menses improves during menstruation.

Lumps are palpated mainly in the upper outer quadrant.

A non-bloody nipple discharge may be reported.

Ultrasound may help to diagnose benign cystic breast tissue.

Mammography is only indicated to help with diagnosis of fibrocystic disease in older women, not adolescents, because the density of breast tissue in adolescents makes interpretation difficult.

Mastodynia

Mastalgia may be cyclic or non-cyclic with menstruation.

There should be no symptoms or signs of breast inflammation.

Specific tests are not indicated. Diagnosis is based on history and

examination.

Breast trauma

Trauma may cause fat necrosis, which could manifest as a breast mass.

Signs of inflammation are uncommon.

Imaging studies may mimic carcinoma (as also occurs on occasion with breast infection).

A biopsy may be indicated for a definitive diagnosis.

Primary invasive breast cancer

The signs and symptoms of breast cancer may be similar to those of breast infection.

It may present as a hard, irregular, painless mass that may or may not be fixed to the underlying tissue.

There may be a nipple discharge, nipple or skin retraction, skin oedema (peau d'orange), and regional lymphadenopathy. Paget's disease will involve the nipple.

Inflammatory breast cancer may resemble mastitis with breast enlargement, warmth, tenderness, oedema, erythema, and possible skin discoloration.

Imaging studies, such as mammography, may reveal a mass, increased density, and micro-calcification.

Percutaneous biopsy (recommended method), or surgical excision (excisional biopsy) if indicated, is necessary to establish the diagnosis.

A skin-punch biopsy for inflammatory breast carcinoma will show tumour infiltration of dermal lymphatics.

Fibroadenoma Presents typically as a non-tender, rubbery, well-circumscribed, and

Imaging studies, such as breast ultrasound and mammography,

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mobile mass.

generally reveal a solid, homogeneous, well-circumscribed, avascular mass with occasional coarse calcification.

Pathological examination will demonstrate a fibroepithelial lesion.

Fat necrosis

Typically results in a tender, round, firm breast mass.

The skin may be dimpled over such a lump.

Inflammation is usually not a common feature unless there is an associated infection.

Breast imaging findings may not be specific.

A breast biopsy is the most accurate means of providing a definitive diagnosis.

Diabetes

May manifest with one or more hard, irregular, mobile, discrete, painless, palpable masses.

Complications arising from diabetes such as retinopathy, neuropathy, and nephropathy may be present.

Breast lesions tend to be recurrent and bilateral.

Patients may have other autoimmune diseases.

Breast imaging studies may be non-specific and can mimic cancer.

Biopsy shows sclerosing lobular lymphocytic mastitis.

Mondor's disease

Thrombophlebitis of a superficial vein may cause breast pain and a cord-like mass with possible skin dimpling, usually in the lower quadrants.

The cord is accentuated by traction, elevation of the breast, or abduction of the ipsilateral arm.

Mammography and a microbiology work-up are usually negative.

Systemic lupus erythematosus

A history of SLE is highly suggestive.

There may be a tender mass lesion with possible skin changes.

Chronic mastitis with flares may be reported.

Serological evidence of lupus is usually present.

Mammography may show architectural distortion, fat necrosis, or calcifications. [43]

A biopsy may help, showing lupus panniculitis.

Necrotising fasciitis

Patients may have fever, chills, and extreme pain associated with rapidly advancing skin erythema,

Laboratory tests may show leukocytosis, elevated urea, and reduced serum sodium level.







and possible cyanosis, vesicles, bullae, ulcers, crepitation, and a black necrotic eschar.

Examination by an experienced surgeon is critical.

A history of prior trauma, skin biopsy, or a surgical wound in the mammary region may be reported.

Infection can be diagnosed with rapid streptococcal diagnostic kits, if available.

Microbiology studies and excisional deep skin biopsy may be helpful in diagnosing and identifying the causative organisms and confirming the diagnosis.

Hidradenitis suppurativa

Presents mainly around hair follicles in the axilla and intertriginous regions under the breasts.

Lesions range from comedones to painful lumps, abscesses, and skin scarring, and these may be associated with a purulent discharge.

A biopsy will show acute and chronic folliculitis with a possible foreign body giant cell inflammation.

Costochondritis

There is localised sternal pain, often exacerbated with respiration or activity.

Pain may radiate. A palpable swelling with redness

is often located about 4 cm from the sternal edge.

A breast examination is usually unremarkable.

Tests are not necessary.

Neonatal breast hypertrophy

Benign breast enlargement may be transient.

The breast bud in such cases is not red or tender.

If present, a nipple discharge is milky and not purulent.

Tests are not necessary.

Gigantomastia Massive hypertrophy of the breasts may occur early in pregnancy.

There may be associated skin necrosis.

Microbiology studies may be required to exclude underlying infection.




Step-by-step diagnostic approach

The diagnosis of mastitis and/or breast infection warrants a detailed history to include potential risk factors, along with a thorough physical examination. While the diagnosis of breast infection is usually made on clinical grounds, investigations may be necessary in certain cases.

Presence of risk factors

Risk factors strongly associated with mastitis include:

Female gender Age 15 to 45 years or adolescence Infants <2 months of age Lactation, particularly after 6 to 8 weeks of breastfeeding or at weaning Poor breastfeeding technique (may also be due to infant factors such as tongue-tie) Milk stasis (may be secondary to poor breastfeeding technique or tight-fitting bra) Nipple injury Previous mastitis Shaving or plucking areolar hair Anatomical breast defect, mammoplasty, or scar Other underlying breast condition particularly breast cancer Nipple piercing Foreign body (e.g., silicone implant) Skin infection Positive carrier status for Staphylococcus aureus Presence of a hospital-acquired infection Immunosuppression (including diabetes mellitus).

Breast abscess is strongly associated with prolonged mastitis and prior breast abscess.

These factors need to be specifically considered when a patient history is taken.

Focused history

A focused history needs to evaluate for:

Symptoms related to possible breast inflammation (e.g., warmth, pain, swelling, firmness, erythema)

Possible abscess (tender lump) Milk stasis (decreased milk output) Systemic infection (fever, malaise, myalgia) Nipple discharge, which may be present with mastitis and occurs more often with duct ectasia

(dilated ducts with inflammation); however, purulent discharge is usually indicative of breast infection.

Physical examination

The diagnosis of breast infection is usually made on clinical grounds. General physical examination includes:

Recording the patient's temperature: mastitis may occur with or without a pyrexia of >38°C (100.4°F); breast abscess may or may not be accompanied by fever.

Checking for other signs of systemic infection (e.g., flu-like illness, possible extra-mammary skin lesions)

Examining for distant skin infections Checking for possible extra-mammary TB infection, including signs of pleural-pulmonary disease,

lymphadenitis, and erythema nodosum.

Breast examination consists of a thorough examination of both breasts and axillary lymph nodes:

Tender axillary lymph nodes may occur with ipsilateral breast infection. Signs of breast inflammation include breast tenderness, warmth, firmness, swelling, and erythema. Lactational mastitis tends to involve more peripheral wedge-shaped areas of the breast. A tender palpable breast mass may indicate localised mastitis or breast abscess. A fluctuant mass may be palpated in the case of a late breast abscess. Rarely, nipple retraction or inversion may occur with mastitis.

If a fistula is present, it is usually associated with a draining sinus from an underlying abscess.

Initial investigations

If mastitis develops unexpectedly, such as in an adolescent, a pregnancy test should be considered.

Ultrasonography, if available, of an erythematous breast area may help in the initial work-up to diagnose an underlying abscess and can direct needle aspiration drainage. [32] View image View image An abscess may appear as a well-circumscribed, macrolobulated, irregular, or ill-defined echo-poor compound cystic lesion with possible septae. [33] [34] A hypoechoic rim may indicate a thick wall of a chronic abscess. Ultrasound is the preferred imaging modality in adolescents, and is applicable in neonates with suspected breast infection. [35] Increased breast density results in the reduced efficacy of mammography in young women.

A breast abscess can be drained by needle aspiration for therapeutic and diagnostic purposes. Aspirated material (fluid, pus, blood) from needle drainage of an abscess should be sent for microbiology studies and cytology to look for underlying malignancy in addition to infection.







Microbiology and pathology investigations

For routine cases of mastitis, a biopsy is not necessarily indicated. For all other cases, such as a suspected abscess, atypical presentation, uncertain diagnosis, or a potential complication (e.g., recurrent infection or treatment failure), a biopsy may be warranted.

A biopsy includes fine-needle aspiration biopsy (which can be performed with/without ultrasound guidance) and tissue biopsy (which may be an excisional or incisional biopsy involving a core-needle biopsy, other vacuum-assisted device, or a formal surgical procedure).

Fine-needle aspiration biopsy and/or nipple discharge should be sent for evaluation of a possible malignancy as well as infection. [36] View image Tissue biopsy permits examination of involved tissue for infection, granulomatous inflammation, and malignancy. Excised tissue should be sent for histopathological evaluation (cytology) for a possible malignancy and infection (e.g., fungal stains and acid-fast bacilli for TB), especially in refractory and recurrent cases. Skin-punch biopsy can be undertaken to diagnose inflammatory breast carcinoma.

Milk, nipple discharge, aspirated material, or excised tissue can be sent for Gram stain, culture (aerobic and anaerobic) with sensitivity, and fungal and mycobacterial studies.

Culture may be performed in all patients or only in selective cases such as:

Hospital-acquired infection Severe or unusual cases Failure to respond to antibiotics within 2 days Recurrent mastitis. [1]

Expressed milk or a midstream milk sample can be sent for leukocyte counts and microbiology studies, including bacteria quantification. [37] Endogenous breast flora is similar to that present on the skin. Although the presence of pathogenic bacteria and/or high bacterial counts (>10^3/mL of milk) indicates mastitis, the predictive value is low. Therefore, the presence of bacteria in milk does not necessarily indicate infection. [1] Moreover, many lactating women who have potentially pathogenic bacteria on their skin or in their milk will not develop mastitis. [1] Alternatively, many women who do develop mastitis may not have pathogenic organisms in their milk. [1] Blood cultures should be obtained in patients who appear toxic and in neonates before initiation of antibiotic therapy. In neonates, additional samples (e.g., cerebrospinal fluid, urine) should be submitted for microscopy and culture.

Mammography

Mammography may be too painful to perform on a breast with an abscess. Also, mammographic findings of breast infection and abscess are non-specific. [33] [34] [38] [39] Breast infection, including TB, can cause the following mammographic findings:

No abnormality Focal/diffusely increased density Architectural distortion A spiculated mass Skin thickening or retraction Micro-calcification.












The findings may mimic cancer. Therefore, mammography is most useful after the acute phase has resolved. At this stage it can help to identify underlying breast lesions. It should be ordered in women >40 years of age, and whenever the presentation is complicated or atypical, or malignancy is suspected. [40]

Additional investigations

A FBC with a differential and blood cultures are indicated in patients with suspected systemic infection, abscess, recurrent infection, or treatment failure.

Previously, investigations recommended in this setting included a serum prolactin level, although evidence now suggests it is not of value. [41]

Tests to diagnose possible TB include a tuberculin skin test (PPD, often positive in patients with active disease), microbiology studies, and/or biopsy.

When lactational mastitis is suspected, examination of the neonate should be considered, specifically with regard to the oral cavity, skin, and nappy area. For recurrent cases of lactational mastitis, cultures from the infant's and mother's oral cavity and nasopharynx are submitted to determine their staphylococcal carrier status.

Diagnostic criteria

Milk counts [37]

Lactational mastitis can be classified according to milk leukocyte counts and quantification for bacteria.

Leukocyte counts and bacteria quantification in breast milkChart produced by author using data from Thomsen AC, Espersen T, Maigaard S. Am J Obstet Gynecol. 1984;149:492-495

Endogenous breast flora is similar to that present on the skin. Although the presence of pathogenic bacteria and/or high bacterial counts (>10^3/mL of milk) indicates mastitis, the predictive value is low. Therefore, the presence of bacteria in milk does not necessarily indicate infection. [1] Moreover, many lactating women who have potentially pathogenic bacteria on their skin or in their milk will not develop mastitis. [1] Alternatively, many women who do develop mastitis may not have pathogenic organisms in their milk. [1]







Treatment OptionsAcute

Patient group Treatment line Treatmenthide all

lactational mastitis

symptoms not severe or not prolonged: no systemic signs and negative culture

1st

effective milk removal and supportive care

In an early stage, when signs and symptoms of mastitis have not been present for more than 12 to 24 hours, it may be possible to manage the condition without antibiotics. [46] [47] [48]

However, antibiotics are required if the pain becomes severe, if milk or blood culture is positive, or if there are any signs of systemic infection.

Breastfeeding should continue frequently (e.g., breastfeeding 8 to 12 times per day) to promote effective milk removal.

Breast pumping on the affected side if indicated and/or massage, if tolerated, may also be used.

The patient should receive support in terms of counselling and breastfeeding advice, and analgesia if necessary (e.g., paracetamol, ibuprofen).

The patient should be advised to increase her fluid intake, try warm and/or cold compresses, and have bed rest.

symptoms severe or prolonged or systemic signs: MRSA excluded by culture or not prevalent in area and no penicillin allergy

1st oral anti-staphylococcal penicillin

Antibiotics are indicated for patients with acute pain, severe symptoms, or symptoms lasting more than 12 to 24 hours; fever or any other signs of systemic infection; or positive microbiology studies.

An oral penicillin with activity against methicillin-sensitive staphylococci could be used first if MRSA has been excluded by culture or if MRSA is not known to be prevalent in the area, and the patient is not allergic to penicillin.

Antibiotic therapy may have to be altered depending on the specific pathogens isolated and corresponding antibiotic susceptibilities.

Treatment course: 10 to 14 days.

Primary Options

flucloxacillin : 250-500 mg orally four times daily




Acute


OR

dicloxacillin : 250-500 mg orally four times daily

OR

cloxacillin : 250-500 mg orally four times daily

plus

[?]






adjunct

[?]

antifungal therapy for mother and infant

If nipple candidiasis is diagnosed, both mother and infant must be treated simultaneously.

Items that have been in contact with maternal nipples should be boiled for 20 minutes.

Clothing that is in contact with the breast should be cleaned with a dilute bleach solution. [60]

Topical cream should be used in the mother, combined with topical suspension for use in the infant.

Treatment course: continue for 2 days after resolution of infection.

Primary Options

nystatin topical : mother: (100,000 units/g) apply to the affected area(s) twice daily

and

nystatin : infant: (100,000 units/mL) 2 mL orally four times daily


Acute


OR

miconazole topical : mother: (2%) apply to the affected area(s) twice daily

and


OR

ketoconazole topical : mother: (2%) apply to the affected area(s) twice daily

and


2nd vancomycin or other antibiotic with activity against MRSA and re-assess diagnosis

Infections should begin to respond within 48 hours. If the infection is worsening despite oral therapy, intravenous vancomycin should be considered instead.

Alternatively, other antibiotics with activity against MRSA may be used (but experience with these other agents in treating mastitis is limited).


In refractory cases an ultrasound scan should be performed looking for possible underlying abscess, a biopsy should be considered, and cultures should be performed to exclude atypical micro-organisms and/or a multi-drug-resistant pathogen.

If a fistula is detected, it needs to be excised (fistulectomy) along with its feeding duct. [50]

Antibiotic treatment course: 10 to 14 days.

Primary Options

vancomycin HCl : 15 mg/kg intravenously every 12 hours,


Acute


maximum 4 g/day

Secondary Options

linezolid : 600 mg intravenously/orally every 12 hours

OR

tigecycline : 100 mg intravenously as a single dose, followed by 50 mg every 12 hours

OR

daptomycin : 6 mg/kg intravenously once daily

plus

[?]






adjunct

[?]







Primary Options


Acute



and


OR


and


OR


and


symptoms severe or prolonged or systemic signs: MRSA confirmed by culture or prevalent in area, or penicillin allergy

1st non-beta-lactam antibiotic

Antibiotics are indicated for patients with acute pain, severe symptoms, or symptoms lasting more than 12 to 24 hours; fever or any other signs of systemic infection; or positive microbiology studies.

If MRSA has been confirmed by culture, or if MRSA is known to be prevalent in the area, then a broad-spectrum antibiotic with community-acquired MRSA (CA-MRSA) coverage is given. This would normally be an oral antibiotic.

Generally most of these patients are outpatients, so the MRSA infection is community-acquired.

This type of antibiotic would also be appropriate if the patient is allergic to penicillin.

The mother should not continue to breastfeed in the

Acute


first 2 months if trimethoprim/sulfamethoxazole is used.

Doxycycline can be used for CA-MRSA infections, during which time the mother should not breastfeed.


Vancomycin may be indicated first-line in hospitalised patients with severe infection. This covers hospital-acquired MRSA.


Primary Options

clindamycin : 300-450 mg orally four times daily

OR

trimethoprim/sulfamethoxazole : 160/800 mg orally twice daily

OR

vancomycin HCl : 15 mg/kg intravenously every 12 hours, maximum 4 g/day

Secondary Options

doxycycline : 100 mg orally twice dailyplus

[?]


Generally, breastfeeding should continue frequently (e.g., breastfeeding 8 to 12 times per day) to promote effective milk removal.

However, if the mother is treated with doxycycline she should not breastfeed. Also, she should not breastfeed if the infant is younger than 2 months old and she is being treated with trimethoprim/sulfamethoxazole.



Acute



adjunct

[?]







Primary Options


and


OR


and


OR


and


Acute



2nd

vancomycin (if not already used first-line) or other antibiotic with activity against MRSA and re-assess diagnosis




In refractory cases an ultrasound scan should be performed looking for possible underlying abscess, a biopsy should be considered, and cultures should be performed to exclude atypical micro-organisms and/or a multi-drug-resistant pathogen.

If a fistula is detected it needs to be excised (fistulectomy) along with its feeding duct. [50]


Primary Options


Secondary Options


OR


OR

daptomycin : 6 mg/kg intravenously once dailyplus

[?]


Generally, breastfeeding should continue


Acute


frequently (e.g., breastfeeding 8 to 12 times per day) to promote effective milk removal.

However, if the mother is treated with doxycycline she should not breastfeed. Also, she should not breastfeed if the infant is younger than 2 months old and she is being treated with trimethoprim/sulfamethoxazole.




adjunct

[?]







Primary Options


and


OR

miconazole topical : mother: (2%) apply to the affected


Acute


area(s) twice daily

and


OR


and


non-lactational mastitis in adults and adolescentsadults: MRSA excluded by culture or not prevalent in area and no penicillin allergy

1st oral anti-staphylococcal penicillin or topical therapy plus supportive care

In early stages it can be difficult to differentiate between non-infectious and infectious non-lactational mastitis, so antibiotics are generally commenced in all cases.

An oral penicillin with activity against methicillin-sensitive staphylococci could be used first if MRSA has been excluded by culture or if MRSA is not known to be prevalent in the area, and the patient is not allergic to penicillin.


If infection is isolated to the nipple, then topical therapy (e.g., topical mupirocin or a polymyxin-containing preparation) may be sufficient.

Supportive care includes analgesia if required. Antibiotic treatment course: 10 to 14 days.

Primary Options


Acute


OR

dicloxacillin : 250-500 mg orally four times daily

OR

cloxacillin : 250-500 mg orally four times daily

OR

mupirocin topical : (2%) apply to the affected area(s) two to three times daily

OR

bacitracin/neomycin/polymyxin B topical : apply to the affected area(s) two to three times daily

plus

[?]

switch to appropriate therapy for underlying cause if needed

Antifungal therapy (e.g., fluconazole) is indicated for deep fungal infections.

TB of the breast requires 6 months of anti-TB therapy including 2 months with a 4-drug combination (e.g., ethambutol, rifampin, isoniazid, and pyrazinamide) followed by 4 months with a 2-drug combination (isoniazid and rifampin). [49]

A lack of response to anti-TB therapy or a diffusely deformed breast with draining sinuses may require surgical intervention.

For post-operative wound infections, a surgeon should be consulted.

Bacterial contamination of a breast implant or any infected foreign body (e.g., nipple ring) is an indication for removal of the foreign body.

For granulomatous mastitis (idiopathic granulomatous inflammation), glucocorticosteroids are the treatment of choice, and surgery is not necessary.

2nd vancomycin or other antibiotic with activity against MRSA and re-assess diagnosis

Infections should begin to respond within 48 hours. If the infection is worsening despite oral therapy, intravenous vancomycin should be considered


Acute


instead. Alternatively, other antibiotics with activity against

MRSA may be used (but experience with these other agents in treating mastitis is limited).


In refractory cases an ultrasound should be performed looking for possible underlying abscess, a biopsy should be considered, and cultures should be performed to exclude atypical micro-organisms and/or a multi-drug-resistant pathogen.



Primary Options


Secondary Options


OR


OR


[?]




A lack of response to anti-TB therapy or a diffusely deformed breast with draining sinuses may require



Acute


surgical intervention. For post-operative wound infections, a surgeon

should be consulted. Bacterial contamination of a breast implant or any

infected foreign body (e.g., nipple ring) is an indication for removal of the foreign body.


adults: MRSA confirmed by culture or prevalent in area or penicillin allergy

1st non-beta-lactam antibiotic plus supportive care

In early stages it can be difficult to differentiate between non-infectious and infectious non-lactational mastitis, so antibiotics are generally commenced in all cases.

If MRSA has been confirmed by culture or if it is known to be prevalent in the area, then a broad-spectrum antibiotic with community-acquired MRSA (CA-MRSA) coverage is given. This is normally an oral antibiotic.


This type of antibiotic would also be appropriate if the patient is allergic to penicillin.

Vancomycin may be indicated first-line in hospitalised patients with severe infection. This covers hospital-acquired MRSA.


Supportive care includes analgesia if required. Antibiotic treatment course: 10 to 14 days.

Primary Options


OR


OR

Acute



Secondary Options

doxycycline : 100 mg orally twice daily

plus

[?]








2nd vancomycin (if not already used first-line) or other antibiotic with activity against MRSA and re-assess diagnosis




In refractory cases an ultrasound scan should be performed looking for possible underlying abscess, a biopsy should be considered, and cultures should


Acute


be performed to exclude atypical micro-organisms and/or a multi-drug-resistant pathogen.



Primary Options


Secondary Options


OR


OR

daptomycin : 6 mg/kg intravenously once daily

plus

[?]










Acute


adolescents (age 12-17 years): MRSA excluded by culture or not prevalent in area and no penicillin allergy

1st

oral anti-staphylococcal penicillin plus supportive care

In adolescents, initial antibiotic treatment can usually be oral. Initial antibiotics for adolescents, if MRSA can be excluded, may include an oral penicillin with activity against methicillin-sensitive staphylococci (e.g., dicloxacillin, cloxacillin, or flucloxacillin, depending on availability).


Supportive measures include analgesia for pain relief if necessary and warm/cold compresses if tolerated.


Primary Options


OR

dicloxacillin : children <40 kg: 12.5 to 25 mg/kg/day orally given in 4 divided doses; children >40 kg: 125-250 mg four times daily

OR

cloxacillin : children <20 kg: 50-100 mg orally four times daily; children >20 kg: 250-500 mg orally four times daily

2nd re-assess diagnosis and treatment

Infections should begin to respond within 48 hours. If there is no response after 48 hours, the patient should be re-assessed.

The regimen should be broadened to include activity against MRSA.

Adolescents with a systemic infection should be treated parenterally (generally with vancomycin). Alternatives include linezolid, tigecycline, or daptomycin.


Acute



Primary Options


Secondary Options


OR


OR

daptomycin : 6 mg/kg intravenously once dailyadolescents (age 12-17 years): MRSA confirmed by culture or prevalent in area or penicillin allergy


In adolescents, initial antibiotic treatment can usually be oral.

In areas where MRSA is prevalent or suspected, and in cases of penicillin allergy, initial treatment should include clindamycin, trimethoprim/sulfamethoxazole, or doxycycline (the latter only in children >8 years of age).


Adolescents with a systemic infection should be treated parenterally (generally with vancomycin).

Also, adolescents with severe infection who are hospitalised should be treated with vancomycin to cover hospital-acquired MRSA.



Primary Options


Acute


OR


OR


OR


2nd

re-assess diagnosis and treatment

Infections should begin to respond within 48 hours. If there is no response after 48 hours, the patient

should be re-assessed. Adolescents who have developed systemic

infection should be treated parenterally (generally with vancomycin), if this has not already been used first-line. Alternatives include linezolid, tigecycline, or daptomycin.


Primary Options


Secondary Options


OR


OR

daptomycin : 6 mg/kg intravenously once dailymastitis in neonates, infants, and children (<12 years)

Acute


MRSA excluded by culture or not prevalent in area and no penicillin allergy

1st

intravenous anti-staphylococcal penicillin or first-generation cephalosporin plus supportive care

Neonates, infants, and children suspected to have mastitis should be referred to a paediatric specialist for management.

They should generally be treated with parenteral antibiotics until bacteraemia can be ruled out. [25]

If MRSA can be excluded by culture, initial antibiotic treatment should consist of an anti-staphylococcal penicillin (e.g., nafcillin, oxacillin, or flucloxacillin, depending on availability) or a first-generation cephalosporin (e.g., cefazolin).


Antibiotic treatment course: 7 to 10 days

Primary Options

flucloxacillin : infants and children: 25-50 mg/kg intravenously every 4-6 hours; consult specialist for guidance on neonatal doses

OR

nafcillin : infants and children: 50-200 mg/kg/day intravenously given in divided doses every 4-6 hours, maximum 12 g/day; consult specialist for guidance on neonatal doses

OR

oxacillin : infants and children: 100-200 mg/kg/day intravenously given in divided doses every 6 hours, maximum 12 g/day; consult specialist for guidance on neonatal doses

OR

cefazolin : infants and children: 25-100 mg/kg/day intravenously given in divided doses every 6-8 hours, maximum 6 g/day; consult specialist for guidance on neonatal doses


Acute


plus

[?]


The diagnosis and treatment will need to be re-assessed, with adjustment made if there is no response to antibiotics within 48 hours.

If initial treatment did not include an agent with activity against MRSA and there has been no response to antibiotics within 48 hours, the regimen should be broadened.

Antibiotic therapy should be adjusted depending on the specific pathogen(s) isolated.

For susceptible gram-negative pathogens, an aminoglycoside (e.g., gentamicin, tobramycin, or amikacin) or a third-generation cephalosporin (e.g., cefotaxime or ceftriaxone) should be included.

Serum aminoglycoside should be monitored regularly according to local protocols to prevent nephrotoxicity and neurotoxicity.

MRSA confirmed by culture or prevalent in area or penicillin allergy


Neonates, infants, and children suspected to have mastitis should be referred to a paediatric specialist for management.

They should generally be treated with parenteral antibiotics until bacteraemia can be ruled out. [25]

In cases where MRSA is isolated or suspected, and it is community-acquired, trimethoprim/sulfamethoxazole can be used in infants older than 2 months of age.

Infants less than 2 months of age may be treated with clindamycin.

Vancomycin is used first-line if the child is ill with systemic symptoms including fever, chills, and anorexia, or hospital-acquired MRSA is suspected.



Primary Options

trimethoprim/sulfamethoxazole : children >2 months of age: 8-10 mg/kg/day intravenously/orally given in divided doses every 12 hours


Acute


More

OR

clindamycin : infants and children: 20-40 mg/kg/day intravenously given in 3-4 divided doses, or 10-20 mg/kg/day orally given in 3-4 divided doses; consult specialist for guidance on neonatal doses

OR

vancomycin HCl : infants and children: 15 mg/kg intravenously every 8 hours; consult specialist for guidance on neonatal doses

plus

[?]




For gram-negative pathogens an aminoglycoside (e.g., gentamicin, tobramycin, or amikacin) or a third-generation cephalosporin (e.g., cefotaxime or ceftriaxone) should be included.

breast abscess

adult: MRSA excluded by culture or not prevalent in area and no penicillin allergy

1st intravenous or oral antibiotic with activity against methicillin-sensitive staphylococci plus supportive care

The patient with a breast abscess, which may or may not be associated with mastitis, requires antibiotic therapy.

If MRSA can be excluded, a breast abscess can be treated with an intravenous or oral antibiotic that is active against methicillin-sensitive staphylococci.

Supportive measures include analgesics if required. Antibiotic treatment course: 7 to 10 days.

Primary Options



Acute


OR

dicloxacillin : 500 mg orally four times daily

OR

cefalexin : 500 mg orally three times daily

OR


OR


OR

flucloxacillin : 0.5 to 2 g intravenously every 6 hours

OR

oxacillin : 1-2 g intravenously every 4-6 hours

OR

nafcillin : 1-2 g intravenously every 4-6 hours

OR

cefazolin : 1-2 g intravenously every 8 hoursplus

[?]




The antibiotic regimen may be broadened to cover MRSA.

If gram-negative bacilli are isolated, a quinolone (e.g., levofloxacin) can be used, if the patient is not breastfeeding. Alternatively, a third-generation cephalosporin (e.g., ceftriaxone or cefotaxime) can

Acute


be used for infection with gram-negative bacilli.

adjunct

[?]

surgical intervention

Surgical intervention is required for mature fluctuant abscesses.

Needle aspiration (18- to 19-gauge needle) with or without ultrasound guidance can be used to drain an abscess. [53] [54] [55] [56] [57] [58] [59]

Aspiration gives excellent palliation and cosmesis. Multiple aspirations over time (daily aspiration for

5 to 7 days) may be necessary for complete drainage, which can be followed by ultrasound if available.

Incision and drainage should be reserved for patients in whom aspiration fails and/or for large abscesses (>5 cm in diameter).[B Evidence]

Percutaneous catheter drainage has also been used with success.[C Evidence]

Purulent material should be submitted for microbiology studies and cytological examination. Antibiotics should be continued for up to 10 days after drainage. If the abscess is <5 cm in diameter and there is no associated cellulitis, antibiotics may not be required.

If the incision does not interfere with breastfeeding, a lactating mother can continue to nurse. If the incision does interfere with nursing on an affected breast, milk can be regularly removed with a breast pump.

adult: MRSA confirmed by culture or prevalent in area or penicillin allergy


Where community-acquired MRSA (CA-MRSA) is suspected or confirmed, or in a patient with a penicillin allergy, trimethoprim/sulfamethoxazole, doxycycline, or clindamycin can be used. Mother should not continue to breastfeed on trimethoprim/sulfamethoxazole if the infant is younger than 2 months of age. Mother should not breastfeed at all if on doxycycline.

Vancomycin can be used in more severe cases and in hospitalised patients where hospital-acquired MRSA is suspected.

Alternatives, especially for patients exhibiting signs of systemic illness, include linezolid, tigecycline,

http://bestpractice.bmj.com/best-practice/monograph/1084/treatment/evidence/score/1.html









Acute


and daptomycin. Supportive measures include analgesics if required. Antibiotic treatment course: 7 to 10 days.

Primary Options


OR


OR


OR

vancomycin HCl : 15 mg/kg intravenously every 12 hours

Secondary Options


OR


OR


[?]




If gram-negative bacilli are isolated, a quinolone (e.g., levofloxacin) can be used, if the patient is not breastfeeding. Alternatively, a third-generation cephalosporin (e.g., ceftriaxone or cefotaxime) can

Acute


be used for infection with gram-negative bacilli.

adjunct

[?]



Needle aspiration (18- to 19-gauge needle) with or without ultrasound guidance can be used to drain an abscess. [53] [54] [55] [56] [57] [58] [59]

Aspiration gives excellent palliation and cosmesis. Multiple aspirations over time (daily aspiration for

5 to 7 days) may be necessary for complete drainage, which can be followed by ultrasound if available.

Incision and drainage should be reserved for patients in whom aspiration fails and/or for large abscesses (>5 cm in diameter).[B Evidence]

Percutaneous catheter drainage has also been used with success.[C Evidence]

Purulent material should be submitted for microbiology studies and cytological examination. Antibiotics should be continued for up to 10 days after drainage. If the abscess is <5 cm in diameter and there is no associated cellulitis, antibiotics may not be required.

If the incision does not interfere with breastfeeding, a lactating mother can continue to nurse. If the incision does interfere with nursing on an affected breast, milk can be regularly removed with a breast pump.

neonate, infant, or child: MRSA excluded by culture or not prevalent in area and no penicillin allergy

1st antibiotic with activity against methicillin-sensitive staphylococci plus supportive care

If MRSA can be excluded, a breast abscess can be treated with an intravenous antibiotic that is active against methicillin-sensitive staphylococci.

Duration of antibiotic treatment will depend on clinical response.

Doxycycline may only be used in children >8 years of age.

Supportive measures include analgesics if required. Antibiotic treatment course: 7 to 10 days.

Primary Options










Acute


dicloxacillin : children <40 kg: 12.5 to 25 mg/kg/day orally given in 4 divided doses; children >40 kg: 125-250 mg every 6 hours for 7-10 days; use in neonates is not recommended

OR

flucloxacillin : children: 12.5 to 25 mg/kg orally four times daily; consult specialist for guidance on neonatal doses

OR

cefalexin : infants and children: 25-100 mg/kg/day orally given in 3-4 divided doses, maximum 4 g/day; use in neonates is not recommended

OR

doxycycline : children >8 years of age: 2.2 mg/kg orally once daily

OR


Secondary Options

flucloxacillin : infants and children: 25-50 mg/kg intravenously every 4-6 hours; consult specialist for guidance on neonatal doses

OR

oxacillin : infants and children: 50-200 mg/kg/day intravenously given in divided doses every 4-6 hours, maximum 12 g/day; consult specialist for guidance on neonatal doses

OR

nafcillin : infants and children: 100-200 mg/kg/day

Acute


intravenously given in divided doses every 6 hours, maximum 12 g/day; consult specialist for guidance on neonatal doses

OR

cefazolin : infants and children: 25-100 mg/kg/day intravenously given in divided doses every 6-8 hours, maximum 6 g/day; consult specialist for guidance on neonatal doses

plus

[?]




If gram-negative bacilli are isolated, a third-generation cephalosporin (e.g., ceftriaxone or cefotaxime) can be used.

Vancomycin can be used in more severe cases.

adjunct

[?]



In a pre-pubertal child, care must be taken to avoid injury to the breast bud. For this reason, in neonates, needle aspiration is preferred and, if required, a small peripheral incision should be made.

neonate, infant, or child: MRSA confirmed by culture or prevalent in area or penicillin allergy


Where community-acquired MRSA (CA-MRSA) is suspected or confirmed, or in a patient with a penicillin allergy, trimethoprim/sulfamethoxazole or clindamycin can be used. Doxycycline may only be used if the child is >8 years old.

Vancomycin can be used in more severe cases and in hospitalised patients where hospital-acquired MRSA is suspected.

Supportive measures include analgesics if required.

Acute



Primary Options

trimethoprim/sulfamethoxazole : children >2 months of age: 8-10 mg/kg/day intravenously/orally given in divided doses every 12 hours

More

OR

doxycycline : children >8 years of age: 2.2 mg/kg orally once daily

OR


OR

vancomycin HCl : infants and children: 15 mg/kg intravenously every 8 hours; consult specialist for guidance on neonatal doses

plus

[?]




If gram-negative bacilli are isolated, a third-generation cephalosporin (e.g., ceftriaxone or cefotaxime) can be used.

adjunct

[?]



In a pre-pubertal child, care must be taken to avoid injury to the breast bud. For this reason, in neonates, needle aspiration is preferred and, if


Acute


required, a small peripheral incision should be made.

Ongoing

Patient group Treatment line

Treatmenthide all

breast abscess post acute intervention

1st

consideration of further surgical intervention

After the acute phase has subsided, chronically infected tissue and the major lactiferous duct associated with the abscess leading to the nipple may need to be excised.[C Evidence]

recurrence of mastitis and/or breast abscess

1st

re-assessment and treatment

Recurrence may occur with delayed therapy, a short course of therapy, inappropriate therapy, and in Staphylococcus carriers. Recurrent mastitis or persistence of a mass after therapy may be due to a breast abscess or underlying breast lesion.

Granulomatous mastitis has a high recurrence rate. Smoking cessation should also be encouraged to

minimise the risk of recurrence.

Treatment approach

The goal of treatment for mastitis is to provide prompt and appropriate management to prevent complications such as a breast abscess. Neonatal/paediatric mastitis treatment is best managed by a paediatrician. Patients with a breast abscess are referred to a surgeon for definitive care. [44]

Lactational mastitis

Treatment includes: [45]

Antibiotic therapy Effective milk removal Warm compresses





Symptomatic relief Supportive counselling.

In an early stage, when signs and symptoms of mastitis are not severe, or have not been present more than 12 to 24 hours, it may be possible to manage the condition without antibiotics. [46] [47] [48] Antibiotics are indicated for patients with:

Acute pain Severe symptoms or lasting more than 12 to 24 hours Fever Systemic infection Positive microbiology studies.

Since Staphylococcus aureus is the most common pathogen, antibiotics with activity against staphylococci should be used. In many regions, the majority of isolates are resistant to methicillin. If MRSA can be excluded by culture or if not prevalent in the area, initial antibiotics may include oral dicloxacillin, cloxacillin, or flucloxacillin (depending on availability) for 10 to 14 days.

In areas where MRSA is common, or in penicillin-allergic patients, clindamycin or trimethoprim/sulfamethoxazole is indicated. Generally most of these patients are outpatients, and these antibiotics are indicated to treat community-acquired MRSA (CA-MRSA). These antibiotics would not be indicated if hospital-acquired MRSA was suspected. The mother should not continue to breastfeed while the infant is younger than 2 months old if trimethoprim/sulfamethoxazole is used. Doxycycline can also be used for CA-MRSA infections, during which time the mother should not breastfeed. Lactational mastitis due to CA-MRSA infection is frequently reported in women who are otherwise healthy and lack traditional risk factors for hospital-acquired MRSA. [CDC: postpartum mastitis and community-acquired methicillin-resistant Staphylococcus aureus] (external link) [12]

Infections should begin to respond within 48 hours. If the infection is worsening despite oral therapy or if the infection is severe and occurs in a hospitalised patient, intravenous vancomycin can be used. This antibiotic covers both CA-MRSA and hospital-acquired MRSA. Other antibiotics with activity against MRSA, including linezolid, tigecycline, and daptomycin, can be used in refractory cases, but experience with these agents in treating mastitis is limited. They are expensive and information is lacking regarding levels in breast milk. Antibiotic therapy may have to be altered depending on the specific pathogens isolated and corresponding antibiotic susceptibilities.

Effective milk removal may involve continued frequent nursing (e.g., breastfeeding 8 to 12 times per day), breast pumping on the affected side if indicated, and/or massage if tolerated.

Supportive measures should include:

Analgesia for pain relief if necessary (e.g., paracetamol, ibuprofen) Increased fluid intake Warm and/or cold compresses Bed rest Supportive counselling.

Patients may require hospital admission for parenteral antibiotic therapy, pain management, and/or surgical intervention, particularly if they:


http://www.cdc.gov/EID/content/13/2/298.htm

http://www.cdc.gov/EID/content/13/2/298.htm




Are immunosuppressed Appear toxic (e.g., bacteraemia/sepsis is suspected) Are haemodynamically unstable Exhibit a rapidly progressive infection Fail outpatient antibiotic therapy.

When nipple candidiasis is diagnosed, both mother and infant must be treated simultaneously. For recurrent cases, cultures from the infant's and mother's oral cavities and nasopharynx are submitted to determine their staphylococcal carrier status.

As an additional point, bromocriptine is not recommended in the management of this condition.

Non-lactational mastitis in adults

Initial treatment for infectious and non-infectious non-lactational mastitis involves appropriate antimicrobial therapy. Generally, even if the indications for antibiotics (as described above) are not met, patients are commenced on antibiotics at an early stage without any period of observation. It can be very difficult to differentiate between non-infectious and infectious non-lactational mastitis at this stage, so antibiotics are used in all cases.

An isolated nipple infection can be treated with topical therapy (e.g., mupirocin 2% or a polymyxin-containing preparation).

For infectious non-lactational mastitis:

Antibiotic therapy and indications for admission are identical to those outlined for lactational mastitis.

Antifungal therapy (e.g., fluconazole) is indicated for deep fungal infections. TB of the breast requires 6 months of anti-TB therapy including 2 months with a 4-drug

combination (e.g., ethambutol, rifampin, isoniazid, and pyrazinamide) followed by 4 months with a 2-drug combination (isoniazid and rifampin). [49] A lack of response to anti-TB therapy or a diffusely deformed breast with draining sinuses may require surgical intervention.

For post-operative wound infections, a surgeon should be consulted. Bacterial contamination of a breast implant or any infected foreign body (e.g., nipple ring) is an

indication for removal of the foreign body. Supportive measures should include analgesia for pain relief if necessary.

Treatment for non-infectious non-lactational mastitis:

Is initially the same as that for infectious mastitis, with antibiotic therapy. [2] [23] For granulomatous mastitis (idiopathic granulomatous inflammation), corticosteroids are the

treatment of choice, and surgery is not necessary. Supportive measures should include analgesia for pain relief if necessary.

Neonatal/paediatric/adolescent mastitis

Neonates and infants suspected to have mastitis should be referred to a paediatric specialist for management. They should generally be treated with parenteral antibiotics until bacteraemia can be ruled out.




If MRSA can be excluded by culture, initial antibiotic treatment should consist of a penicillin that is active against methicillin-sensitive staphylococci (e.g., nafcillin, oxacillin, or flucloxacillin, depending on availability), or a first-generation cephalosporin (e.g., cefazolin).

In cases where MRSA is isolated or suspected, and it is community-acquired, clindamycin or, in infants older than 2 months of age, trimethoprim/sulfamethoxazole can be used. If the infection is worsening and in cases of MRSA in an ill child or a hospitalised child (where hospital-acquired MRSA is suspected), vancomycin should be used. Antibiotic therapy should be adjusted depending on the specific pathogen(s) isolated. For gram-negative pathogens an aminoglycoside (e.g., gentamicin, tobramycin, or amikacin) or third-generation cephalosporin (e.g., cefotaxime or ceftriaxone) should be included.

In adolescents, initial antibiotic treatment can usually be oral. Initial antibiotics for adolescents, if MRSA can be excluded, may include an oral penicillin (e.g., dicloxacillin, cloxacillin, or flucloxacillin, depending on availability) that is active against methicillin-sensitive staphylococci, for 10 to 14 days. In areas where MRSA is prevalent or suspected, and in cases of penicillin allergy, initial treatment should include clindamycin, trimethoprim/sulfamethoxazole, or doxycycline (the latter only in children >8 years of age). Generally most of these patients are outpatients, and these antibiotics are indicated to treat community-acquired MRSA (CA-MRSA).

Infections should begin to respond within 48 hours. If there is no response after 48 hours, the patient should be re-assessed. If initial treatment did not include an agent with activity against MRSA, the regimen should be broadened. Adolescents with a systemic infection should be treated parenterally (generally with vancomycin). Also, adolescents with severe infection who are hospitalised should be treated with vancomycin to cover hospital-acquired MRSA. Alternatives include linezolid, tigecycline, or daptomycin. Supportive measures include analgesia for pain relief if necessary and warm/cold compresses if tolerated.

Refractory cases

In refractory cases, the following diagnoses should be considered:

Multiple and/or deep abscess Coexistent malignancy Underlying breast abnormality Fistula Fungal infection TB Atypical mycobacteria Other unusual infectious pathogen or multi-drug resistance Granulomatous mastitis.

An ultrasound should be performed looking for possible underlying abscess. A biopsy should be considered. Cultures should be performed to exclude atypical micro-organisms and/or a multi-drug-resistant pathogen. If a fistula is detected it needs to be excised (fistulectomy) along with its feeding duct. [50]



Breast abscess

The patient with a breast abscess, which may or may not be associated with mastitis, requires antibiotic therapy. Studies have found that breast abscesses in women admitted with puerperal mastitis were most commonly associated with community-acquired MRSA (CA-MRSA). [51] [52] If MRSA can be excluded, a breast abscess can be treated with an intravenous or oral antibiotic that is active against methicillin-sensitive staphylococci. In cases of suspected or confirmed CA-MRSA, or in a patient with a penicillin allergy, trimethoprim/sulfamethoxazole, doxycycline, or clindamycin can be used. Vancomycin may be used in more severe cases and in hospitalised patients where hospital-acquired MRSA is suspected. Alternatives in adults, especially for patients exhibiting signs of systemic illness, include linezolid (oral or intravenous), tigecycline (intravenous), and daptomycin (intravenous). If gram-negative bacilli are isolated, a quinolone can be used in adults if the patient is not breastfeeding. Alternatively, a third-generation cephalosporin (e.g., ceftriaxone or cefotaxime) can be used.

For an early abscess presenting as an indurated mass, a course of antibiotics may suffice. For a mature abscess (e.g., fluctuant mass), surgical intervention along with antibiotics is indicated.

Needle aspiration (18- to 19-gauge needle) with or without ultrasound guidance can be used to drain an abscess. [53] [54] [55] [56] [57] [58] [59] Aspiration gives excellent palliation and cosmesis. Multiple aspirations over time (daily aspiration for 5 to 7 days) may be necessary for complete drainage, which can be followed by ultrasound if available. Incision and drainage should be reserved for patients in whom aspiration fails and/or for large abscesses (>5 cm in diameter).[B Evidence]

Percutaneous catheter drainage has also been used with success.[C Evidence] Purulent material should be submitted for microbiology studies and cytological examination. Antibiotics should be continued for up to 10 days after drainage. If the abscess is <5 cm in diameter, and there is no associated cellulitis, antibiotics may not be required.

After the acute phase has subsided, chronically infected tissue and the major lactiferous duct associated with the abscess leading to the nipple may need to be excised.[C Evidence] If the incision does not interfere with breastfeeding, a lactating mother can continue to nurse. If the incision does interfere with nursing on an affected breast, milk can be regularly removed with a breast pump.

In a pre-pubertal child, care must be taken to avoid injury to the breast bud. For this reason, in neonates, needle aspiration is preferred and, if required, a small peripheral incision should be made. Pain medication should be prescribed as necessary.

Recurrence of mastitis and/or breast abscess

May occur with delayed therapy, a short course of therapy, inappropriate therapy, and in Staphylococcus carriers. Recurrent mastitis or persistence of a mass after therapy may be due to a breast abscess or underlying breast lesion. Granulomatous mastitis has a high recurrence rate. Smoking cessation should also be encouraged to minimise the risk of recurrence.













Emerging treatments

Oxytocin nasal spray

This can be attempted in lactational mastitis to facilitate the letdown reflex and aid emptying of the breast. [26]

Vitamins

Vitamin E may help with mastitis. Supplements with retinol, vitamin A, and beta-carotene have not been shown to prevent subclinical mastitis, [2] and in a study in HIV-positive women, actually increased the risk of subclinical mastitis. [61]

Monitoring

Following therapy, patients should be re-examined (e.g., using ultrasonography) for development of a potential abscess that may need to be drained. An inflammatory mass that does not respond to therapy should be biopsied to exclude underlying carcinoma or an unusual infection. For women >40 years of age, breast imaging studies, such as mammography, should be performed after resolution of the acute process to exclude unsuspected underlying breast cancer.

Patient Instructions

Patients should seek medical help if their symptoms do not improve within 48 hours after antibiotic therapy for mastitis, or if a tender breast lump develops that is not relieved by breastfeeding. They should contact a paediatrician if their nursing child shows signs of illness or develops a nappy rash while the mother is taking antibiotics. Patients can be reassured that a breast infection does not increase the chances of developing breast cancer. [14] On-line patient information from recommended sources may be helpful for breastfeeding mothers. [NHS Choices. Mastitis (breastfeeding).] (external link) [NHS Choices. Breastfeeding guide.] (external link) Information concerning non-lactational mastitis and breast abscess is also available. [NHS Choices. Mastitis (non-breastfeeding).] (external link) [NHS Choices. Breast abscess.] (external link)

Complications

Complicationhide all Timeframe Likelihood

cessation of breastfeeding short term medium

http://www.nhs.uk/conditions/breast-abscess/Pages/Introduction.aspx

http://www.nhs.uk/conditions/breast-abscess/Pages/Introduction.aspx

http://www.nhs.uk/conditions/mastitis-non-breastfeeding/Pages/introduction.aspx

http://www.nhs.uk/planners/breastfeeding/pages/breastfeeding.aspx

http://www.nhs.uk/planners/breastfeeding/pages/breastfeeding.aspx

http://www.nhs.uk/conditions/mastitis/Pages/Introduction.aspx






The development of mastitis may lead to the cessation of breastfeeding.

However, an abrupt cessation of breastfeeding may exacerbate the symptoms of mastitis, and there is an increased risk of breast abscess.

Effective treatment and support from healthcare workers and family are important. [63]

abscess (complicating mastitis)

Less than 10% of patients with mastitis are likely to develop a breast abscess.

short term low

sepsis

see our comprehensive coverage of Sepsis

Any breast infection may be associated with bacteraemia, particularly in very young and immunosuppressed patients.

short term low

scarring

Breast infection, including an abscess that is adequately treated, is unlikely to cause significant breast scarring.

Surgical intervention other than needle aspiration may cause a post-operative scar.

Recurrent infections, TB, and granulomatous mastitis can cause significant breast deformity.

long term low

functional mastectomy

This refers to a breast that is unable to effectively lactate as a complication of prior tissue destruction from infection or treatment.

long term low

breast hypoplasia

Damage to the infant breast bud from scarring and/or surgical intervention may cause subsequent breast asymmetry and/or hypoplasia.

long term low

necrotising fasciitis

see our comprehensive coverage of Necrotising fasciitis

Mastitis may be the initiating event for necrotising fasciitis, particularly in childhood. [62]

variable low

extra-mammary skin infection

Patients with Staphylococcus aureus mastitis are at risk for subsequent skin

variable low





infections at extra-mammary sites.

fistula

Spontaneous rupture of an abscess can lead to a draining sinus with a resulting fistula.

A mammary fistula occurs in 1% to 2% of women. [6]

Prognosis

When treated promptly and appropriately, most breast infections including abscess will resolve without serious complications. Most patients will have resolution of mastitis after 2 to 3 days of appropriate antibiotic therapy.

Breastfeeding

Most patients with breast infection can continue to breastfeed, with the exception of those who are HIV infected. [1] Nursing mothers should not breastfeed if they are being treated with trimethoprim/sulfamethoxazole and the infant is less than 2 months of age. Doxycycline is contra-indicated in breastfeeding women.

Recurrence

Mastitis may recur with delayed therapy, inappropriate therapy, uncorrected poor breastfeeding technique, nipple candidiasis, an underlying breast condition, and in Staphylococcus carriers. Recurrent mastitis or persistence of a mass after therapy may be due to a breast abscess or underlying breast lesion. Granulomatous mastitis has a high (up to 50%) recurrence rate.



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