Oral Cephalosporin with Good CSF Penetration
There is no oral third-generation cephalosporin with clinically adequate CSF penetration for treating CNS infections. All third-generation cephalosporins recommended for bacterial meningitis require intravenous administration 1.
Why Oral Cephalosporins Are Not Suitable for CNS Infections
The third-generation cephalosporins with proven efficacy for meningitis (ceftriaxone, cefotaxime, ceftazidime) are not available in oral formulations and must be given intravenously to achieve therapeutic CSF concentrations 2, 3. The guidelines explicitly state that none of the third-generation compounds suitable for CNS infections can be administered orally 3.
Limited Data on Oral Cephalosporin CSF Penetration
- Cefpodoxime proxetil, an oral third-generation cephalosporin, achieves only approximately 5% CSF penetration after oral administration 4
- While this minimal penetration may reach MIC90 for some susceptible pathogens, cefpodoxime is not indicated for bacterial meningitis treatment 4
- The low CSF concentrations are only clinically relevant in that they may obscure CSF culture results in patients developing meningitis while on oral antibiotics 4
Recommended Parenteral Third-Generation Cephalosporins
For actual treatment of CNS infections requiring cephalosporins, intravenous administration is mandatory:
- Ceftriaxone and cefotaxime are the most extensively studied and recommended agents for common meningeal pathogens (S. pneumoniae, H. influenzae, N. meningitidis) 1, 2
- These agents achieve CSF concentrations of 2.21-5.36 μg/mL with CSF/serum ratios of 3.73-31.80% during acute purulent meningitis 5
- Ceftazidime is preferred when Pseudomonas aeruginosa coverage is needed 2
Critical Clinical Pitfall
Do not attempt to treat bacterial meningitis or other serious CNS infections with oral cephalosporins. The CSF penetration is inadequate regardless of meningeal inflammation 4, 3. Intravenous third-generation cephalosporins remain the standard of care for cephalosporin-responsive CNS infections 1.