Cefazolin is a first-generation cephalosporin antibiotic administered intravenously (IV) or intramuscularly (IM). It was introduced in the early 1970s and is available under brand names like Ancef and Kefzol.
Mechanism of Action and Microbial Coverage
Cefazolin, a beta-lactam antibiotic, inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to bacterial death. It covers many Gram-positive bacteria, including most Staphylococcus aureus (except MRSA) and Streptococcus species, and some Gram-negative bacteria like Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis.
Clinical Uses of Cefazolin
Cefazolin is used to treat and prevent various bacterial infections, such as skin and soft-tissue, respiratory, urinary tract, bone and joint infections, and endocarditis. It is particularly important for surgical prophylaxis to prevent surgical site infections.
Cefazolin vs. Other Antibiotics
Cefazolin is often chosen for surgical prophylaxis. While effective against many Gram-positive and some Gram-negative bacteria, it is ineffective against MRSA or Pseudomonas. A comparison with other antibiotics is shown in the table below:
| Feature | Cefazolin | Cephalexin | Vancomycin/Clindamycin | Third-Gen Cephalosporin | Fourth-Gen Cephalosporin |
|---|---|---|---|---|---|
| Generation | First | First | Not applicable | Third | Fourth |
| Administration | IV or IM injection only | Oral (capsules, liquid) | IV (mostly) or oral | IV, IM, or oral | IV |
| Primary Use | Surgical prophylaxis, moderate to severe infections | Milder skin/soft tissue infections, UTIs | Alternative for penicillin/cefazolin allergy; specific resistant infections | Broader Gram-negative coverage; meningitis | Very broad spectrum; severe resistant infections (Pseudomonas) |
| Gram-Positive | Excellent | Excellent | Excellent (Gram-positive only) | Good | Excellent |
| Gram-Negative | Modest (E. coli, K. pneumoniae) | Modest | Poor | Enhanced | Excellent (includes Pseudomonas) |
| Key Advantage | High and prolonged serum levels, excellent bone penetration | Oral convenience | Effective against MRSA | Enhanced Gram-negative coverage | Broadest spectrum, good CNS penetration |
Administration
Administration is determined by infection type and severity, patient weight, and kidney function. For surgical prophylaxis, it is typically given before surgery. For active infections, it's given at regular intervals. Careful consideration of patient factors is crucial.
Side Effects and Precautions
Allergic reactions, especially for those with penicillin allergies, are a key concern, though cross-reactivity risk is low for many.
Common Side Effects may include nausea, vomiting, diarrhea, headache, injection site reactions, or candidiasis.
Serious Side Effects requiring immediate attention include severe allergic reactions, Clostridium difficile-associated diarrhea (CDAD), kidney problems, or seizures.
Precautions involve informing your doctor about certain medical histories. Cefazolin is generally considered safe during pregnancy (Category B) and breastfeeding but requires medical consultation. It is ineffective against viral infections.
Conclusion
What is cefazolin? It is an important injectable first-generation cephalosporin antibiotic used for treating bacterial infections and preventing surgical infections. For more detailed clinical information, resources such as {Link: US National Library of Medicine https://www.ncbi.nlm.nih.gov/books/NBK551517/} are available.
