CNS Penetration of Antibiotics

Clinical Implications for CNS Infections

• The Infectious Diseases Society of America recommends alternative agents with better CSF penetration, such as linezolid (66% penetration into CSF), for CNS infections 2
• Trimethoprim-sulfamethoxazole is also recommended, with penetration rates of 13-53% for TMP and 17-63% for SMX into CSF 2
• Meropenem is recommended for nosocomial meningitis/ventriculitis, according to the Infectious Diseases Society of America 3
• Therapeutic drug monitoring (TDM) of beta-lactams is recommended when treating CNS infections, with sampling of both blood and CSF when possible, as suggested by the Society of Critical Care Medicine 4, 5
• The target concentration in CSF should be above the MIC of the isolated bacteria, as recommended by the Society of Critical Care Medicine 5
• Surgical drainage of focal abscesses and removal of any foreign body should be performed whenever possible to improve treatment outcomes, as recommended by the Infectious Diseases Society of America 2

Risk of Neurotoxicity

• Beta-lactams can cause neurotoxicity, particularly at high concentrations, according to the Society of Critical Care Medicine 6, 7
• Piperacillin has a relatively low pro-convulsive activity (11% relative to penicillin G) compared to other beta-lactams, as reported by the Society of Critical Care Medicine 7
• Plasma steady-state concentration of piperacillin above 157 mg/L is predictive of neurological disorders in ICU patients, with a specificity of 97% and sensitivity of 52%, as found by the Society of Critical Care Medicine 7
• The risk of neurotoxicity increases when free plasma concentration exceeds 8 times the MIC, as warned by the Society of Critical Care Medicine 6, 7