Giving antibiotics before surgery is critical in reducing post-operative infections. In fact, one study showed a reduction in absolute risk of wound infection for patients getting knee/hip replacements by over 80%. This is usually given right before incision, but ultimately needs to be given within 60 minutes of surgical start time so that the blood concentration of antibiotics is greatest during the surgery.
The typical organism that can be found on the skin and have potential to cause an infection are Staphylococcus auereus, S. epidermidis, and streptococci. Cefazolin is a cephalosporin antibiotic that has a relatively narrow spectrum of coverage that makes it a good candidate for surgical prophylaxis purpose.
Cefazolin is a beta-lactam, similar to penicillins. Patients commonly have historical “allergic” reactions to penicillins as a kid, such as a rash, headache, or nausea. When this is the case, we typically still use Cefazolin as the antibiotic of choice for 2 reasons. First, there is little cross-reactivity between penicillins and cephalosporins in terms of adverse reactions. And secondly, the benefit of preventing a post-surgical infection far outweighs the risk of a rash or nausea.
However, if a patient has a history of anaphylaxis to a cephalosporin in the past, you will want to pick a different agent. Most places will use either Vancomycin or Clindamycin. Vancomycin is also used for patients who are at high-risk for a MRSA (methicillin-resistant staph auereus) infection or had a previous MRSA infection. Depending on the surgical site, it may call for broader spectrum of bacterial coverage, like including anaerobic bacteria for pelvic surgery. In this case, you may add on antibiotics such as Metronidazole (Flagyl).
Typical dosing for Cefazolin is 2g and 3g if the patient is over 120kg. The dose for Vancomycin is 15 mg/dl. Cefazolin is redosed every 4 hours (if the surgery is still progressing) or if the patient has lost over 1500ml of blood.
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2 окт 2024
