Cefazolin (Ancef)

Anesthesia Implications

Classification: 1st generation cephalosporin antibiotic, beta-lactam
Therapeutic Effects: Antibiotic

Contraindications

Absolute – Patients that have a specific allergy to cefazolin or cephalosporins. Patients that have an active MRSA infection.

Relative – Patients that have seizures (especially with renal impairment), beta-lactam alergy (eg. penicillin), colitis, or renal impairment. MOST patients with a beta-lactam allergy are able to tolerate cefazolin (see “Additional Notes”)

Primary Considerations

Use – Cefazolin is FDA approved for infections of skin and soft tissue, bones and joints, urinary tract, respiratory tract, biliary tract, bloodstream, genital infection, endocarditis, cellulitis.

Timing – The antibiotics should be given at least 30 min before surgery but no greater than 60 minutes before. If using a tourniquet, the antibiotic is LEAST effective if administered after the tourniquet is inflated.

Redosing – Intraoperatively, if the surgical duration is greater than 4 hours OR there is greater than 1500 ml of blood loss, then cefazolin should be redosed. Antibiotic coverage should be continued for 24 hours postoperatively.

Scope – Ancef is not typically used in surgical sites where the probable infectious bacteria would not be covered by Ancef alone (eg. colorectal, appendectomy, etc).

Alternatives – Cindamycin or vancomycin are most often used as alternatives when Ancef is contraindicated.

Penicillin (PCN) Allergy – MOST patients with a penicillin allergy history may safely receive cefazolin. See “Additional Notes”.

Side Effects – Pruritus, induration/phlebitis at injection site. IgE-mediated urticaria (hives), angioedema, anaphylaxis (<1-6 hours after). T-cell-mediated maculopapular rash (7-14 days after). Abdominal cramps, diarrhea, nausea.

IV push dose

Adult

less than 120 kg – 2 grams
greater than or equal to 120 kg – 3 grams
kidney impairment (CrCl less than 30 mL/min) – 1g

Pediatric

30 mg/kg (MAX 2 grams)

*Prepared by reconstituting 1gram of powder with 5ml of sterile water/crystalloid.

Method of Action

Ancef binds to penicillin binding proteins → inhibit bacterial cell wall synthesis → cell lysis

Elimination

Renal – Excreted unchanged by renal glomerular filtration

Additional Notes
Generations – Cephalosporins have five “generations”, the earlier generations are more active against gram-positive bacteria, while the most recent generations are more active against gram-negative bacteria.

Antimicrobial Spectrum
Gram-positive bacteria – methicillin-susceptible Staphylococcus aureus (MSSA), coagulase – negative Staphylococci, penicillin-susceptible Streptococcus pneumoniae, Streptococci spp.
Gram-negative bacteria – Moraxella catarrhalis, Escherichia coli, Klebsiella pneumoniae,
Proteus mirabilis

Beta-Lactam cross-reactivity – Cefazolin is a non-cross-reactive cephalosporin; Cross-reactivity is based on studies of 1960’s Cephalothin (Keflin) with a similar side-chain to PCN. Cefazolin shares the PCN beta-lactam ring, but has two different side-chains. The rate of any reaction to cefazolin with a history of true IgE Type I Hypersensitivity to PCN is 1-4%, but the rate of anaphylaxis is significantly less and equivocal to those without history of a PCN allergy. Antibodies to PCN also dissipate to 0% at 20 years. In three lawsuits with PCN allergy, the provider administering cefazolin was not convicted due to, “a lack of scientific evidence demonstrating cephalosporins… are contraindicated for patients with a penicillin allergy”.

Alternative antibiotics (clindamycin, vancomycin, gentamycin) may have a 50% higher risk of surgical site infection if used in place of Ancef.