Part VI: Guidelines for Surgical Prophylaxis

Surgical prophylaxis refers to the administration of antibiotics before surgery to prevent surgical site infections (SSIs). It is recommended for most clean-contaminated and specific clean procedures in which the consequence of infection is severe, such as those involving placement of prostheses or implants. [535]

Moreover, patient-specific factors may justify the use of antimicrobial prophylaxis in certain procedures where it might not typically be recommended. Risk factors that may warrant prophylaxis include extremes of age, obesity, diabetes mellitus, and immunosuppression. [536]

SSI is commonly classified into ‘superficial incisional’ (involving only skin and subcutaneous tissue of the incision), ‘deep incisional’ (involving deep soft tissues of the incision for example fascial and muscle layers), and ‘organ-space’ (involving any part of the body deeper than the fascial/muscle layers that is opened or manipulated during the operative procedure). [537]

The causative organisms of SSI are usually skin commensals or flora that are present at the bodily site of operation (for example, Gram-negative and anaerobic bowel flora for surgeries traversing the colon).

The choice, dosing and timing of antimicrobial agent are crucial for the effectiveness of surgical prophylaxis.

Surgical prophylaxis is not a replacement of proper infection control practices.

In cases of contaminated or infected wounds, such as traumatic or bite injuries, ruptured or suppurative viscus, postoperative antibiotic treatment is recommended instead of prophylaxis.

The antimicrobial should target the anticipated pathogens and reach adequate concentration at the site of the incision.

Narrow-spectrum agents are preferred because they pose a lower risk of causing Clostridioides difficile infection and antimicrobial resistance. [538] Other important considerations include local resistance patterns, prior antibiotic use history, and instances of antibiotic-resistant infections.

For many prophylactic antimicrobial agents, the initial dose should be administered within 30 minutes before incision, coinciding with the induction of anaesthesia, to achieve bactericidal serum and tissue concentrations at the time of the initial incision. This process can be facilitated by having the anaesthesiologist administer the drug in the operating room during induction. The antimicrobial agents should be infused completely prior to the incision. [539,540]

When administering surgical prophylaxis for drugs that requires prolonged infusion times (e.g. 2 hours for intravenous 1 g vancomycin, 60 minutes for intravenous 500 mg levofloxacin, 60 minutes for intravenous 400 mg ciprofloxacin), it is important to plan ahead to ensure that the medication is given within the appropriate timeframe before the surgical incision. [535,536]

Screening and decolonisation is recommended for high-risk surgery such as cardiac, orthopaedic and neurosurgery involving implant. In general, mupirocin without proper screening is not advised as indiscriminate use can contribute to the development of resistance. [541,542]

Patients with a history of MRSA colonisation or a recent MRSA infection should receive surgical prophylaxis with MRSA coverage for high-risk surgeries. [535]

The recommended dosages for cefazolin are as follows: 1 g for adult patients weighing ≤80 kg, 2 g for patients weighing 81–120 kg, and 3 g for patients weighing over 120 kg. [535,547,548]

Calculation of dosing for aminoglycosides in obese patients (i.e. actual body weight >20% above the ideal body weight) should be based on patient’s adjusted body weight. [535,549]

Adjusted body weight = Ideal body weight + 0.4 × (Total body weight–Ideal body weight), where:

• Ideal body weight (male) is 50 + 2.3 × (height in inches − 60)

• Ideal body weight (female) is 45.5 + 2.3 × (height in inches − 60)

Self-reported β-lactam allergy has been linked to a higher risk of SSIs due to use of alternative, non-β-lactam and often inferior antibiotics. [550,551]

A β-lactam antibiotic can be used as prophylaxis after thorough consideration and discussion [Please refer to Part VII (Other Issues - Management of Antibiotic Allergy) for more information].

If the antimicrobial agent used to treat the current infection is deemed appropriate for surgical prophylaxis, an extra dose should be administered within 30 minutes before the surgical incision.

If the current antimicrobial agent is insufficient for surgical prophylaxis, additional coverage according to guideline recommendations is required. In the event of uncertainty, please consult a clinical microbiologist or infectious disease physician.

Colonisation of multi-drug resistant organisms (MDRO) other than MRSA and consequent SSI caused by these pathogens are controversial issues. Whether prophylaxis should be expanded to cover for these pathogens depends on many factors, including the host, the MDRO and its antimicrobial susceptibility profile, the procedure and the proximity of the pathogen reservoir to the operative site.

Please consult a clinical microbiologist or infectious disease physician for the use of surgical prophylaxis. [535,552,553]

There is no evidence to suggest that administering prophylactic antimicrobial agents after incisional closure reduces SSIs, even when drains are inserted during the procedure. [549,554–560] On the contrary, antibiotics given after closure can lead to increased antimicrobial resistance, superinfections by fungi and Clostridioides difficile, as well as side effects such as rash and acute kidney injury. [554,561]

A review by the WHO indicates that there is low to very low-quality evidence suggesting that a brief postoperative prophylaxis duration may offer some benefits in reducing SSIs in cardiac and jaw (orthognathic) surgery. However, RCTs in these procedures have not shown any advantage in extending prophylaxis beyond 24 hours. In vascular surgery, evidence from a single RCT suggests that extending prophylaxis until the removal of intravenous lines and tubes may be beneficial in reducing SSI. [554]