Rationale for FDA's Position on Cefadroxil
Cefadroxil is FDA-approved for the treatment of:
- Urinary tract infections caused by E. coli, P. mirabilis, and Klebsiella species.
- Skin and skin structure infections cause by staphylococci and/or streptococci.
- Pharyngitis and/or tonsillitis caused by Streptococcus pyogenes (Group A beta-hemolytic streptococci).
The cefadroxil webpage on the FDA Antibacterial Susceptibility Test Interpretive Criteria (STIC) website does not provide minimum inhibitory concentration (MIC) or disk diffusion breakpoints but includes a statement that, “Susceptibility of Enterobacteriaceae to cefadroxil may be deduced from testing cefazolin.” However, the cefazolin webpage on the FDA STIC website states that, “Separate susceptibility test interpretive criteria for Enterobacteriaceae for therapy of uncomplicated urinary tract infections are not recognized at this time.” Furthermore, it has been shown that cefazolin surrogate susceptibility breakpoints do not accurately predict cefadroxil activity against Enterobacterales due to an unacceptably high false-susceptible rate. To note, cefadroxil STIC, either direct or surrogate, are not provided by the Clinical and Laboratory Standards Institute (CLSI), CLSI M100 Ed32:2022.
Based on the information noted above, the Agency has determined that the following statement should be removed from the FDA STIC webpage for cefadroxil: “Susceptibility of Enterobacteriaceae to cefadroxil may be deduced from testing cefazolin.”