• Antimicrobial medications can be associated with neurological adverse reactions. 
• An individual’s risk is influenced by their age, weight, nutritional status, the medications they are taking concurrently, and pharmacological properties (dosage, half-life, CNS permeability). 
• Encephalopathy 
  • Seen with beta-lactams, fluoroquinolones, clarithromycin, and sulfamethoxazole-trimethoprim. 
  • Most commonly with cefepime. 
  • Higher risk in elderly, renal dysfunction, and preexisting CNS disease. 
• Seizures 
  • Beta-lactams block GABA receptors. 
  • Highest risk with cefepime and imipenem. 
• Peripheral neuropathy 
  • Associated with metronidazole, fluoroquinolones, linezolid, chloramphenicol, and isoniazid. 
  • Most cases are dose dependent. 
  • Some cases are irreversible. 
• Ototoxicity 
  • Aminoglycosides cause cochlear NMDA receptor excitotoxicity. 
• Weakness 
  • Fluoroquinolones, macrolides, and aminoglycosides inhibit acetylcholine release and bind neuromuscular junction receptors. 
  • Should be avoided in myasthenia gravis and Lambert-Eaton syndrome. 
• Movement disorders 
  • Tremors – sulfamethoxazole-trimethoprim 
  • Dyskinesia, dystonic reactions – fluoroquinolones, chloramphenicol 
  • Cerebellar syndrome – metronidazole, aminoglycosides 

Bottom Line: Recognition of antibiotic associated neurotoxicity reduces unnecessary workup and serious adverse effects. 

References

• Vo ML. Commonly used drugs for medical illness and the nervous system. Continuum (Minneap Minn) 2020;26(3, Neurology of Systemic Disease):716-731. 

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