Mania Following Triple Therapy for Helicobacter pylori: A Probable Case of Metronidazole-induced Antibiomania

Antibiotic-induced manic syndromes, or "antibiomania," are rare and not well understood. Clarithromycin and, less commonly, metronidazole have been implicated in such cases. This report aims to present a detailed clinical case and to discuss its relevance in light of current evidence on antibiotic-induced manic reactions.

A 54-year-old woman developed acute mania within 24 hours of starting triple therapy for Helicobacter pylori infection (clarithromycin, metronidazole, amoxicillin). All antibiotics were discontinued, and short-term sedation was initiated, resulting in full remission within 48 hours. One month later, she completed a dual regimen excluding metronidazole (clarithromycin and amoxicillin) without psychiatric relapse.

Using Bégaud's causality algorithm, a "probable" link with metronidazole was established based on rapid onset after first exposure, resolution upon withdrawal, and absence of recurrence on re-exposure without metronidazole. Although clarithromycin's risk cannot be ruled out, the clinical course favors metronidazole. Clarithromycin's metabolite may interfere with GABAergic transmission, while metronidazole exhibits documented central neurotoxicity by an unclear mechanism and minor cytochrome P450 inhibition. Pharmacodynamic effects, either from metronidazole alone or synergistically with clarithromycin, are the most plausible cause. The patient had vulnerability factors including a hyperthymic temperament and prior suicidal behavior.

This case highlights the importance of monitoring mood symptoms during metronidazole therapy, particularly in patients with affective risk factors, and underscores the need for prompt discontinuation upon psychiatric symptoms.