[Antibiomania: A Novel Presentation of a Case of Metronidazole-Induced Neurotoxicity]

Metronidazole is known to induce a characteristic encephalopathy, marked by neurological manifestations and typical MRI abnormalities, whereas psychiatric presentations remain rarely described. To date, no description of a frank manic symptomatology occurring concomitantly with metronidazole-induced encephalopathy has been reported in the literature. Antibiomania is a rare adverse effect defined by the onset of a manic or hypomanic episode in close temporal association with antibiotic exposure. We report the case of a 67-year-old man hospitalized for complex hepatobiliary complications and intermittently and cumulatively exposed to metronidazole and ciprofloxacin. He developed an acute behavioral change characterized by disinhibition, psychomotor agitation, logorrhea with pressured speech, irritability, hallucinatory phenomena, as well as dysarthria and falls. Brain MRI revealed T2 hyperintensities involving the dentate nuclei, red nuclei, tectal plate, and splenium of the corpus callosum, findings consistent with metronidazole-induced encephalopathy. Discontinuation of antibiotics was followed by rapid clinical improvement, with no recurrence after reintroduction of ciprofloxacin alone. This case highlights a previously undescribed clinical presentation combining typical metronidazole-induced encephalopathy with a frank manic syndrome. It underscores the importance of considering antibiomania in the differential diagnosis of a first acute manic episode in order to enable early discontinuation of the causative antibiotic.