No, Do Not Give Cefazolin After Ceftriaxone Has Already Been Administered
There is no indication to administer cefazolin after ceftriaxone has already been given for surgical prophylaxis in hip surgery. Ceftriaxone provides adequate coverage for the target organisms in orthopedic surgery, and adding cefazolin would be redundant, wasteful, and potentially expose the patient to unnecessary antibiotic-related adverse effects without any clinical benefit 1.
Why Cefazolin Should Not Be Added
Overlapping Spectrum and Redundancy
- Both cefazolin (first-generation cephalosporin) and ceftriaxone (third-generation cephalosporin) target the same organisms responsible for surgical site infections in orthopedic procedures, primarily Staphylococcus aureus and Staphylococcus epidermidis 1.
- Ceftriaxone has a broader spectrum than cefazolin and covers all the organisms that cefazolin would cover, plus additional Gram-negative bacteria 2.
- Adding cefazolin after ceftriaxone provides no additional antimicrobial coverage that isn't already achieved by ceftriaxone alone 3.
Duration and Timing Principles
- Surgical antibiotic prophylaxis should be limited to the operative period, sometimes 24 hours, exceptionally 48 hours, and never beyond 1.
- A single preoperative dose is proven effective for most interventions, with re-injection only needed if surgery duration exceeds the antibiotic's half-life coverage window 1.
- Since ceftriaxone has already been administered, the prophylactic window is covered—there is no rationale for "switching" or "adding" cefazolin 1.
Antibiotic Stewardship Concerns
- Unnecessary antibiotic administration increases costs without clinical benefit 4.
- Excessive antibiotic exposure increases the risk of Clostridioides difficile infection and other adverse effects 4.
- The principle "more must be better" has no pharmacokinetic or clinical basis when adequate tissue concentrations are already achieved 4.
When Ceftriaxone Is Acceptable (Though Not Preferred)
Efficacy Evidence
- Meta-analysis demonstrates that ceftriaxone is as effective as cefazolin in preventing surgical site infections across multiple surgical disciplines 3.
- However, one retrospective study in orthopedic upper extremity surgery showed a significantly higher deep SSI rate with ceftriaxone (1.1%) compared to cefazolin (0.08%), with an odds ratio of 12.9 (p=0.005) 5.
Guideline Preference
- Cefazolin remains the preferred first-line agent for orthopedic surgery prophylaxis due to its optimal pharmacokinetics, safety profile, and cost-effectiveness 1, 6.
- The standard regimen for hip surgery is cefazolin 2g IV slow, single dose, with re-injection of 1g if surgery duration exceeds 4 hours 1.
- Ceftriaxone may be used as an alternative when cefazolin is unavailable (as occurred during the 2019 cefazolin shortage), but it is not the guideline-recommended first choice 5.
Common Pitfalls to Avoid
- Do not "double up" on cephalosporins: Once ceftriaxone has been given, the prophylactic coverage is established. Adding cefazolin serves no purpose 1, 3.
- Do not extend prophylaxis beyond 24-48 hours: The presence of surgical drains does not justify prolonged antibiotic administration 1.
- Do not re-dose at drain removal: There is no evidence supporting antibiotic administration during removal of drains, probes, or catheters 1.
What to Do Instead
- Continue with the ceftriaxone that has already been administered and follow standard prophylaxis duration guidelines (single dose or up to 24 hours maximum) 1.
- Monitor for surgical site infection using standard postoperative surveillance protocols 1.
- For future cases, use cefazolin 2g IV as the first-line agent for hip surgery prophylaxis, reserving ceftriaxone only when cefazolin is contraindicated or unavailable 1, 5.