• Summary
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• Background
• Clinical Diagnosis
• Investigation
• Treatment
• Non-Antimicrobial Treatment
• Empirical Antimicrobial Treatment
• Directed Antimicrobial Treatment (when microbiology results are known)
• Duration of Treatment
• Switch to oral agent(s)
• Treatment Failure

Diagnosis

• Localised breast swelling and erythema and pain/tenderness and/or
• Purulent discharge from nipple
• Assess systemic symptoms of infection (fever, vomiting etc.) and history of breast disease, surgery or radiotherapy.

Investigations

• Ambulatory/outpatient treatment
• Pus sample (see below).
• Inpatients
• FBC, U&E and CRP
• Pus sample (ideally aseptic aspirate of pus or collection of pus in sterile container-see below) for culture.
• blood culture x2 in patients with systemic signs of infection.
• Breast ultra-sound scan (USS) - to establish diagnosis of abscess or mastitis.
• All patients
• Appropriate breast imaging is usually required once the abscess has resolved to exclude occult malignancy

Non-antimicrobial treatment

Mastitis without breast abscess does not initially require surgical intervention. If an abscess is confirmed on USS:

• Urgent (within 24 hours of diagnosis) ultrasound guided needle aspiration is first-line therapy (in combination with antimicrobial treatment, see below) and is usually repeated within 2-3 days.

• Surgical Incision and drainage is recommended for loculated abscesses or those which fail to resolve with ultrasound guided needle aspiration.

Antimicrobial treatment

Group A. For breast abscess/cellulitis in pregnant or lactating woman** OR post-operative wound infection (<3 weeks post operation)**
Recommended regimen for non-severe infection (outpatient/ambulatory therapy):

• Flucloxacillin  500mg 6-hourly PO, (or for lactating women who delivered at SJUH or LGI between Feb and April 2014, Clindamycin 450mg 6-hourly PO)
• For penicillin allergic patient: Clindamycin 450mg 6-hourly PO
• Note: clindamycin has the potential to cause adverse effects on the breastfed infant's gastrointestinal flora.  Monitor the infant for possible effects on the gastrointestinal flora, such as diarrhoea, candidiasis (thrush, nappy rash) or rarely, blood in the stool indicating possible antibiotic-associated colitis.

Recommended regimen for severe infection (inpatient):

• Flucloxacillin  1-2g 6-hourly IV , or for lactating women who delivered at SJUH or LGI between Feb and April 2014 Clindamycin 450mg 6-hourly IV
• For penicillin allergic patients: Clindamycin 450mg 6-hourly IV

Group B. For Non-lactating women (including sepsis secondary to periductal mastitis and non lactational abscess) ** OR breast skin cellulitis occurring at least 3 weeks after previous breast conserving surgery or mastectomy or breast radiotherapy**
Recommended regimen for non-severe infection (outpatient/ambulatory therapy):

• Co-Amoxiclav (Amoxicillin-Clavulanate)  625mg 8-hourly PO, OR
• For penicillin allergic patient: Clindamycin 300mg 6-hourly PO

Recommended regimen for severe infection (inpatient):

• Co-Amoxiclav (Amoxicillin-Clavulanate)  1.2g 8-hourly IV, OR
  For penicillin allergic patient: Tigecycline 100mg IV loading dose then 50mg 12-hourly. This will need approval from Microbiology.

**If known to be colonized or infected by meticillin resistant Staphylococcus aureus Discuss with Microbiology.

# Linezolid has a number of drug interactions/contraindications. Please see full guidance to check suitability for the patient.

Oral switch: For all patients on IV antimicrobials switch to oral regimens according to oral switch guidelines. Use regimen for “non-severe” breast infection appropriate to group A or B. e.g. patients in group B Tigecycline would be switched to Clindamycin 300mg 6-hourly PO.

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Infection of breast tissue is known as mastitis, which may develop into a localized collection of pus [breast abscess] in a proportion of cases particularly if there is delay in the treatment or inadequate initial treatment. The incidence of breast abscess has been variably reported as 0.4 - 11% of lactating women (Dener & Inan, 2003; Eryilmaz et al., 2005). Infection occasionally spreads to affect areas away from the primary abscess. Breast infection is seen most commonly in women of 18 to 50 years of age (Dixon, 1994). Periductal mastitis is infection in the peri-ariola region typically in smokers, in non-lactating women.
Breast infection occurs in several distinct clinical contexts:

1. In breast feeding women.
2. In non-breast feeding women (typically smokers)
3. In women with advanced breast malignancy (rare).
4. Complicating breast surgery in the immediate post-operative period.
5. In women who have previously had breast conserving surgery or mastectomy, often with radiotherapy

In women who are breastfeeding the abscess can occur in any part of the breast, but in women who are not breastfeeding abscesses usually occur under the nipple and areola.

The most common organisms isolated in puerperal breast abscess and post-surgery are Staphylococcus aureus (Eryilmaz et al., 2005; Moazzez et al., 2007) and less often streptococci. Periductal mastitis commonly involves mixed infection including anaerobes. Breast abscess associated with malignancy typically contain mixed flora (Dixon, 1994).

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History
Check history of previous abscess, breast disease, breast surgery or radiotherapy.
Assess symptoms of fever, vomiting or breast discharge.
Check if lactating.
Check if patient smokes (key risk factor for periductal mastitis)

Examination
Assess localised breast swelling, redness, warmth, pain, discharge from the nipple or mass. Determine if fluctuance is present.
Examine lymph nodes. Check for signs of systemic infection.

NB. Inflammatory breast cancer is not an infection but can mimic mastitis – if a patient fails to respond promptly to antimicrobial treatment of mastitis this diagnosis needs to be excluded urgently by referral to a breast surgeon.

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Ambulatory/outpatient treatment

• Ideally sample pus into a sterile container (a pus swab is adequate but not optimal sampling). [Evidence level C]

Inpatients

• Full blood count, Urea and electrolytes and CRP should be performed.
• Pus sample (ideally aseptic aspirate of pus or collection of pus in sterile container-(see below) for culture.
• blood culture x2 in patients with systemic signs of infection.
• Breast ultra-sound scan (USS) - to establish diagnosis of abscess or mastitis. NB. Early incision and drainage without ultrasound is required for patients where the overlying skin is macerated or there is a discharge of pus.

[Evidence level C]

All patients
Appropriate breast imaging is usually required once the abscess has resolved to exclude occult malignancy.
[Evidence level C]

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Mastitis without breast abscess does not initially require surgical intervention. If an abscess is confirmed on USS:

• Ultrasound guided needle aspiration has been shown to be successful in the treatment of breast abscess in place of surgical incision and drainage. (Eryilmaz et al., 2005; Ulitzsch et al., 2004).
• Urgent (within 24 hours of diagnosis) ultrasound guided needle aspiration is first-line therapy (in combination with systemic antimicrobial treatment, see below) and is usually repeated within 2-3 days, except where the overlying skin is macerated or there is already a discharge of pus: in this group proceed to 3.
• Surgical Incision and drainage is recommended for loculated abscesses or those which fail to resolve with ultrasound guided needle aspiration or where the overlying skin is macerated or there is already a discharge of pus. A patient is considered to have failed to resolve with ultrasound guided needle aspiration when there is no clinical improvement after 72 hours.

NB. Patients should be advised to stop smoking as part of their management.

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The antimicrobial management of mastitis and breast abscesses (not associated with breast surgery) is the same.

Dixon (1994) has recommended oral Flucloxacillin for lactating infection and Co-Amoxiclav (Amoxicillin-Clavulanate)  for non-lactating infection to ensure some anti Gram-negative and anti-anaerobic activity. In penicillin allergic patients, Erythromycin was recommended for lactating infection and Cefradine or Erythromycin in combination with Metronidazole for non-lactating infection (Dixon, 1994). However, Erythromycin is not well tolerated and lacks the anti-anaerobic activity of Clindamycin . There is a move to avoid cephalosporins wherever possible to reduce selection pressure for Clostridium difficile infection.

In one prospective study, ampicillin-sulbactam was given to all breast abscess patients for a period of 10 days unless in abscesses larger that 10cm in diameter where initial treatment was with intravenous ampicillin-sulbactam in the first 72 hours (Eryilmaz et al., 2005). Co-Amoxiclav (Amoxicillin-Clavulanate) has a similar spectrum of activity to ampicillin-sulbactam.

Group A. For breast abscess/cellulitis in pregnant or lactating woman** OR post operative wound infection (<3 weeks post operation)**

Recommended regimen for non-severe infection (outpatient/ambulatory therapy):

• Flucloxacillin  500mg 6-hourly PO, (or for lactating women who delivered at SJUH or LGI between Feb to April 2014, Clindamycin 450mg 6-hourly PO)
• For penicillin allergic patient: Clindamycin 300mg 6-hourly PO
• Note: clindamycin has the potential to cause adverse effects on the breastfed infant's gastrointestinal flora.  Monitor the infant for possible effects on the gastrointestinal flora, such as diarrhoea, candidiasis (thrush, nappy rash) or rarely, blood in the stool indicating possible antibiotic-associated colitis.

Recommended regimen for severe infection (inpatient):

• Flucloxacillin  1-2g 6-hourly IV, or for lactating women who delivered at SJUH or LGI between Feb and April 2014, Clindamycin 450mg 6-hourly IV
• For penicillin allergic patient: Clindamycin 450mg 6-hourly IV

Group B. For Non-lactating women (including sepsis secondary to periductal mastitis and non lactational abscess) ** OR breast skin cellulitis occurring at least 3 weeks after previous breast conserving surgery or mastectomy or breast radiotherapy**

Recommended regimen for non-severe infection (outpatient/ambulatory therapy):

• Co-Amoxiclav (Amoxicillin-Clavulanate)  625mg 8-hourly PO, OR
• For penicillin allergic patient: Clindamycin 300mg 6-hourly PO

Recommended regimen for severe infection (inpatient):

• Co-Amoxiclav (Amoxicillin-Clavulanate)  1.2g 8-hourly IV, OR
• For penicillin allergic patient:  Tigecycline 100mg IV loading dose then 50mg 12-hourly. This will need approval from Microbiology.

**If known to be colonized or infected by meticillin resistant Staphylococcus aureus Discuss with Microbiology.
# Linezolid has a number of drug interactions/contraindications. Please see full guidance to check suitability for the patient.
[Evidence level D]

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Once a microbiological diagnosis is established, switch to directed antimicrobial regimens wherever possible, according to susceptibilities and example regimens below. Therapy may need to be amended on a case-by-case basis according to patient factors.
Recommended regimen for Staphylococcus aureus (meticillin susceptible) infection (inpatient):

• Flucloxacillin  1-2g 6-hourly IV , or
• For penicillin allergic patient: Clindamycin 450mg 6-hourly IV

Oral switch Flucloxacillin 500mg 6-hourly PO

Recommended regimen for Staphylococcus aureus (meticillin resistant) infection (inpatient):

• 1st line Linezolid ^#600mg 12-hourly PO/IV or 2nd line Teicoplanin IV (see dosing guidelines). Oral switch Linezolid ^#600mg 12-hourly PO

^#Linezolid has a number of drug interactions/contraindications. Please see full guidance to check suitability for the patient.

Recommended regimen for Streptococcus pyogenes (group A Streptococcus) infection (inpatient):

• Benzyl penicillin  -1.2g 4-hourly IV , or
• For penicillin allergic patient: Clindamycin 450mg 6-hourly IV

Oral switch Amoxicillin 1g 8-hourly PO

Recommended regimen for Staphylococcus aureus (PVL-associated) infection (inpatient):

• Clindamycin 450mg 6-hourly IV

Oral switch Clindamycin 450mg 6-hourly PO

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All patients were given Flucloxacillin after undergoing US-guided needle aspiration or catheter placement for at least 10 days in one study (Ulitzsch et al., 2004). Hook & Ikeda (1999) recommended 10 day course of antibiotics after abscess drainage but do not expand on the evidence or choice of agent (Hook & Ikeda, 1999).

Recommendation:
Duration of treatment: 7 -10 days according to clinical response. [Evidence level C]

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All patients were given Flucloxacillin after undergoing US-guided needle aspiration or catheter placement for at least 10 days in one study (Ulitzsch et al., 2004). Hook & Ikeda (1999) recommended 10 day course of antibiotics after abscess drainage but do not expand on the evidence or choice of agent (Hook & Ikeda, 1999).

Recommendation:
Duration of treatment: 7 -10 days according to clinical response. [Evidence level C]

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