General Principles

Severe Penicillin / Cephalosporin Allergy

The patient is considered to have a true allergy if they have at least one of: respiratory difficulty, hypotension, or hives. In the absence of these findings, cefazolin can be used as a surgical prophylaxis.


Preoperative doses should be given within 60 minutes before surgical incision, except for vancomycin, which should be given 1-2 hours before incision.


Interoperative repeat dosing is recommended for: prolonged surgical procedures (> 3-4 hours), major blood loss, or other factors that shorten antibiotic half-lives (e.g. extensive burns).

Repeat dosing may NOT be warranted in patients in whom antibiotic half-lives are prolonged (e.g. patients with renal insufficiency or failure).


Postoperative doses are not routinely indicated for routine surgical prophylaxis.

Postoperative antibiotics are used in: cardiac surgery, transplant surgery, cochlear implantation and when infections are found intra-operatively (where antibiotics are used for treatment and not prophylaxis)

Known MRSA Colonization or Infection

For patients with KNOWN MRSA colonization or infection, consider adding vancomycin to the surgical prophylaxis regimen for cardiac, spinal, and orthopedic procedures involving implantation: complex fractures / fractures with internal fixation. Vancomycin alone is less effective than cefazolin for preventing SSI’s due to MSSA