Abstract
A rare case of acute sinusitis in a 62-year-old man caused by Prevotella intermedia is reported. This patient presented with the characteristic features of acute inflammation of the nose and sinuses, which persisted for nearly 50 days. Noteworthy findings included erosive lesions of the middle turbinate, black pigmentation of the nasal mucosa and a viscous material which is characteristic of Prevotella intermedia infection. Doripenem hydrate, foropenem sodium hydrate, and minocycline were effective for the treatment.