What is cefazolin and what are its indications?

Cefazolin: Indications and Clinical Applications

Cefazolin is a first-generation cephalosporin antibiotic primarily indicated for the treatment of various serious bacterial infections and surgical prophylaxis, with excellent safety and efficacy profiles even in patients with non-severe penicillin allergies. 1

Mechanism and Antimicrobial Spectrum

Cefazolin is a beta-lactam antibiotic that works by inhibiting bacterial cell wall synthesis. It demonstrates excellent activity against:

• Gram-positive organisms:

  • Staphylococcus aureus (including beta-lactamase-producing strains)
  • Streptococcus pneumoniae
  • Streptococcus pyogenes (Group A streptococci)

• Gram-negative organisms:

  • Escherichia coli
  • Proteus mirabilis
  • Klebsiella pneumoniae 1, 2

Therapeutic Indications

According to the FDA label, cefazolin is indicated for the following serious infections due to susceptible organisms:

1. Respiratory tract infections: Caused by S. pneumoniae, S. aureus, and S. pyogenes
2. Urinary tract infections: Caused by E. coli and P. mirabilis
3. Skin and skin structure infections: Caused by S. aureus and streptococci
4. Biliary tract infections: Caused by E. coli, streptococci, P. mirabilis, and S. aureus
5. Bone and joint infections: Caused by S. aureus
6. Genital infections: Including prostatitis and epididymitis due to E. coli and P. mirabilis
7. Septicemia: Caused by S. pneumoniae, S. aureus, P. mirabilis, and E. coli
8. Endocarditis: Caused by S. aureus and S. pyogenes 1

Surgical Prophylaxis

Cefazolin is the preferred agent for surgical antibiotic prophylaxis in most procedures:

• Gastrointestinal surgery: First choice (with metronidazole added for colorectal procedures)
• Cardiac surgery: First choice
• Orthopedic surgery: First choice
• Gynecological surgery: First choice (often with metronidazole for hysterectomy)
• Obstetric surgery: First choice for cesarean section
• Neurosurgery: First choice
• Plastic surgery: First choice 3

The Australian Therapeutic Guidelines (2019) and American Society of Health-Systems Pharmacists (2013) both recommend cefazolin as the preferred agent for most surgical prophylaxis procedures 3.

Use in Penicillin-Allergic Patients

Cefazolin has a unique safety profile regarding penicillin allergies:

• Non-anaphylactic penicillin allergy: Cefazolin is safe to use as it does not share side chains with penicillins 3
• Immediate-type penicillin allergy: Cefazolin can be used regardless of severity or time since index reaction, as it does not share side chains with available penicillins 3
• Perioperative prophylaxis: Recent evidence shows that hospital-wide guidelines recommending cefazolin in patients with penicillin allergy labels can increase its use without compromising safety 4

Special Considerations

1. Group B Streptococcal (GBS) prophylaxis: Cefazolin is recommended as an alternative for intrapartum antibiotic prophylaxis in penicillin-allergic women not at high risk for anaphylaxis 3

2. Cardiac device-related infections: Cefazolin (6 g/day for 24-36 hours) is recommended for prophylaxis before cardiac device implantation 3

3. Infective endocarditis: Cefazolin is reasonable in patients with a well-defined history of non-anaphylactoid reactions to penicillins 3

4. Hospital-acquired pneumonia: Cefazolin is preferred for the treatment of proven methicillin-sensitive S. aureus (MSSA) infections, though not typically used in empiric regimens 3

5. Bariatric surgery: Higher doses (4g) are recommended due to patient weight 3

Administration and Dosing

• Standard adult dose: 1-2g every 8 hours
• Surgical prophylaxis: 2g (3g for patients >120kg) within 60 minutes before incision
• Higher doses (4g) may be needed for bariatric surgery patients 3
• For perioperative prophylaxis, cefazolin should usually be discontinued within 24 hours after the surgical procedure 1

Contraindications and Cautions

• Known hypersensitivity to cefazolin or other cephalosporins
• Caution in patients with severe immediate-type (anaphylactic) penicillin allergy, although cross-reactivity is low (estimated at 10%) 3
• Not effective against enterococci, methicillin-resistant S. aureus (MRSA), or Pseudomonas aeruginosa

Conclusion

Cefazolin remains a cornerstone antibiotic for both treatment of various bacterial infections and surgical prophylaxis due to its excellent safety profile, targeted antimicrobial spectrum, and favorable pharmacokinetics. Its unique structure makes it safe even for many patients with penicillin allergies, further expanding its clinical utility.