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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.
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")
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.
Ancef binds to penicillin binding proteins → inhibit bacterial cell wall synthesis → cell lysis
Renal - Excreted unchanged by renal glomerular filtration
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.
