Negative myoclonus as the leading symptom in acute cefepime neurotoxicity.

An 86-year-old woman was diagnosed with hospital-acquired pneumonia with Pseudomonas aeruginosa and treated with cefepime adjusted to her renal clearance. After 4 days, she developed acute-onset negative myoclonus without signs of altered mental status. After ruling out an acute intracranial haemorrhagic or ischaemic stroke as well as other metabolic and endocrine causes of negative myoclonus, the antibiotic was switched to piperacillin/tazobactam due to a suspicion of cefepime neurotoxicity. The patient improved within 24 hours and her symptoms fully resolved within 4 days. These observations suggest a link of the negative myoclonus to acute cefepime neurotoxicity, which may occur without or with minimal alteration of mental status, thus extending its spectrum of clinical presentation.