From the Guidelines
Vancomycin does not cover everything that Ancef (cefazolin) covers, particularly for gram-negative bacteria. Vancomycin is primarily effective against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) 1, but has poor coverage against gram-negative organisms. Cefazolin, a first-generation cephalosporin, provides good coverage against many gram-positive bacteria (though not MRSA) and also covers some gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. This difference in spectrum is important clinically because using vancomycin alone when gram-negative coverage is needed could lead to treatment failure. Some key points to consider include:
- The Infectious Diseases Society of America guidelines recommend vancomycin for MRSA infections, but also suggest other antibiotics like cefazolin for certain types of skin and soft tissue infections 1.
- For necrotizing fasciitis, the guidelines recommend clindamycin plus piperacillin-tazobactam, or ceftriaxone plus metronidazole, which may include vancomycin for MRSA coverage 1.
- The WHO Model List of Essential Medicines includes vancomycin as a watch antibiotic for severe infections, but also lists other antibiotics like amoxicillin-clavulanic acid and cefalexin as first-choice options for mild to moderate skin and soft tissue infections 1. In situations where both MRSA and gram-negative coverage are required, vancomycin would typically need to be combined with another antibiotic that has gram-negative activity. The distinction matters because vancomycin also has more potential for toxicity (including nephrotoxicity and ototoxicity) and requires therapeutic drug monitoring, while cefazolin generally has a better safety profile and doesn't require level monitoring 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Vancomycin and Ancef Coverage
- Vancomycin is a glycopeptide antibiotic effective against gram-positive bacterial infections 2, 3, 4.
- Ancef, also known as cefazolin, is a beta-lactam antibiotic that covers gram-positive bacteria, including methicillin-susceptible Staphylococcus aureus (MSSA) 5.
- Vancomycin has a broader spectrum of activity against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) 5, 6.
- Cefazolin has limited activity against MRSA and some strains of MSSA 5.
Comparison of Vancomycin and Ancef
- Vancomycin is more effective than cefazolin against MRSA and some strains of MSSA 5.
- Cefazolin is less effective than vancomycin against gram-positive bacteria, including MSSA and MRSA 5.
- Vancomycin is active against a wider range of gram-positive bacteria, including Bacillus spp., Corynebacterium spp., Micrococcus spp., viridans group streptococci, Streptococcus pneumoniae, and Streptococcus spp. 6.