Stephan Harbarth, Geneva (CH)
Perioperative antibiotic prophylaxis in surgery is one of the best documented and evidence-based pharmacological measures to prevent surgical site infection (SSI). Its principles are well-defined and based on sound clinical studies. As highlighted by 2 recent systematic reviews, it’s probably one of the areas in infectious diseases with the strongest 1A evidence supporting the choice, drug dosage, administration route and duration of antibiotic administration.
Nevertheless, great variation still exists around the world with respect to compliance with these guidelines. In particular, many surgeons and anesthesiologists still continue antibiotic prophylaxis beyond 24h after operation, although it has been well proven that 1 dose of antibiotic prophylaxis is sufficient in many circumstances.
Principles (based and adapted from a French consensus report, issued in 2010)
The aim of antibiotic prophylaxis (ABP) is to counter bacterial proliferation in order to reduce the risk of SSI. The preoperative visit is the ideal time to decide whether to prescribe ABP. The decision should take into account:
- the type of intervention
- the risk associated with the intervention and therefore whether ABP is warranted or not
- the timing of ABP administration before surgery
- and any history of allergy that might affect the choice of antibiotic.
ABP is applicable to certain clean or clean-contaminated interventions. Infection is already present in the case of contaminated or dirty interventions. These require therapeutic (= curative) antibiotic treatment which is governed by other rules in terms of treatment duration (the first dose is injected preoperatively).
ABP should target bacteria known to be the most common cause of SSI and need not cover all possible bacteria that may be encountered. The ABP protocol should include a drug active against the target bacteria. Evidence for the drug’s activity, local diffusion and tolerability in the given indication should be available from methodologically sound studies. The chosen drugs should have a narrow activity spectrum and have marketing approval for the given indication.
Each hospital team should state in its written ABP protocol the name of the practitioner in charge of supervising ABP prescriptions. This practitioner may be the anaesthetist, surgeon, gastroenterologist, radiologist, or a specialist in another discipline. However, responsibility is always shared with other practitioners: the ABP protocol should state clearly who does what.
The correct timing is crucial: ABP should be administered about 30 minutes before the intervention.
- Practitioners should ensure that their patients have really been prescribed ABP. ABP administration is ticked off on a checklist.
- ABP administration should be of short duration and is usually restricted to the operative period. It may sometimes be prolonged for 24 hours and exceptionally for 48 hours.
- Use of surgical drains does not warrant prolonging administration. There is no need for additional injections on removing drains, probes, or catheters.
- The ABP protocol in routine use also applies to ambulatory surgery.
The loading dose is usually twice the conventional dose.
- In obese patients (Body Mass Index > 35 kg/m2), beta-lactam doses must be double the doses for non-obese patients even for surgery other than bariatric surgery.
Additional injections are given intra-operatively every two half-lives of the antibiotic at a similar dose or at half the loading dose.
- For example, an additional dosage of cefazolin (half-life = 2 hours) is only necessary if the operation lasts longer than 4 hours.
ABP protocols are locally agreed by the department’s surgeons, anaesthetists, specialists in infectious diseases, microbiologists, and pharmacists. A health economic analysis of different options should be performed.
Protocol efficacy is regularly assessed by monitoring SSI rates and causal pathogens in operated patients. Regular practice appraisal is highly recommended. Each establishment or care unit should establish an ABP policy, i.e. make a list of interventions that do or do not qualify for ABP by category, and specify the drug for each category or the alternative in cases of allergy. In addition, patients at high risk of infection should benefit from personally customised ABP. Other situations may also warrant tailoring. ABP protocols must be written down, signed by the anaesthetists and other practitioners. These protocols should be available and possibly displayed in the pre-anaesthesia consultation rooms, operating rooms, recovery rooms, and care units.
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