Guideline for antimicrobial prophylaxis during breast surgery in adults

1. Summary table of routine recommendations
2. Background information
3. Special antimicrobial prophylaxis recommendations

1. Summary table of routine recommendations

**use ideal body weight instead of actual body weight for dosing if BMI>35

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2. Background information

The aim of antimicrobial prophylaxis when used in breast surgery is a reduction in surgical site infection (SSI)- a potentially life-threatening complication.

A review of antimicrobial prophylaxis recommendations for breast surgery in Leeds has been prompted by local audit data indicating a 25% infection rate the continued presence of meticillin-resistant Staphylococcus aureus (MRSA) in the Trust and the ongoing problem of Clostridium difficile infection. It is appropriate to use a single pre-operative dose of prophylaxis in most situations to reduce the risks related to antimicrobial use while gaining maximum benefit from prophylaxis (NICE, SIGN).

These guidelines should be applicable to the majority of patients. Where the recommendations in these guidelines do not seem appropriate for a particular patient, the surgeon or cardiologist is advised to discuss the case with a microbiologist.

Relevant background information pertaining to procedure or microbiology and aims of prophylaxis.

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3. Special antimicrobial prophylaxis recommendations

Understanding surgical site infection (SSI) risk factors after breast operation is essential to develop infection-prevention strategies and improve surgical outcomes. An audit in Leeds identified that up to 25% of patients undergoing mastectomy and axillary node clearance will develop a surgical site infection. Wound infections after breast surgery can have severe consequences, such as poor cosmesis and in the case of breast cancer, can delay subsequent adjuvant chemotherapy and radiation therapy. It has been shown that delaying adjuvant therapy results in worse outcomes for patients with breast cancer. Various factors increase the likelihood of SSI after breast surgery:

1. A large tissue space is often created. Mastectomy and axillary clearance are clean operations. However, an extensive tissue space is created under the mastectomy flaps and in the axilla. Protein rich seroma fluid forms in this space. Drains are used as a temporary measure to remove seroma fluid. Most patients develop a seroma on removal of the drain and as long as this is sterile it will usually resolve over a number of weeks. A similar but often larger tissue space forms in the latissimus dorsi donor site when a latissimus dorsi myocutaneous flap is used for breast reconstruction.
   
   
2. The removal of the axillary lymph nodes often causes congestion in the skin flaps when combined with mastectomy and in the residual breast when combined with a wide local excision. Such patients may exhibit delayed wound healing and typically have a higher incidence of wound infection, both early and late.
   
   
3. Patient’s may receive neodjuvant chemotherapy (NACT) and have their surgery 3-4 weeks after the last cycle to provide the maximum chance of tumour control. They will have received repeated dosing with steroids during the period of NACT. These factors lower the host immunity to wound infection and may contribute to delayed healing.
   
   
4. Patient’s may have previously had chest wall radiotherapy. This reduces the blood supply to the irradiated skin and soft tissues through a permanent process of endarteritis obliterans. Delayed healing and wound infection are a greater risk in this patient cohort¹.
   
   
5. Mastectomy and axillary clearance usually takes an hour to 90 minutes. Breast reduction typically takes over 2-hours. Breast reconstruction may take between 2 and 5 hours depending on the technique used.

When prophylactic antibiotics are not given with breast cancer surgery, breast reduction or breast reconstruction the odds of developing a SSI is approximately five fold higher¹. The longer the breast operation the higher the risk of a SSI and it has been shown in randomised controlled studies that antibiotic prophylaxis reduces this risk². The concomitant use of a drain, which is common in this scenario is also associated with an increased risk of SSi if no prophylaxis is used².

Prophylactic antibiotic use for breast surgery is routine in the vast majority of breast centres in the UK. Co-amoxiclav  is the most common choice because of the spectrum of cover that is afforded. A nationwide survey found that over 80% of surgeons who performed breast augmentations, myocutaneous flap reconstructions and implant reconstructions used antibiotic prophylaxis. Up to 33% used antibiotic prophylaxis for wide local excisions (WLEs), mastectomies and axillary surgery for breast cancer, while 62% and 45% used antibiotics for breast reductions and duct excisions, respectively³.

A recent meta-analysis showed that prophylactic antibiotics substantially reduce the risk of postoperative wound infections in breast surgery⁴. There is also no evidence of high-risk or harmful reactions from administration of prophylactic antibiotics.