Abstract: Shewanella is a gram-negative rod bacterium found particularly in the sea; it is widespread in freshwater, soil, and oilfields, but it is rarely separated from human infection. There are two types of Shewanella strain: S. algae and S. putrefaciens. Bacillemia, spondylodiscitis, meningitis, and brain abscess caused by these bacteria have been reported. We report a rare case of middle ear infection caused by S. putrefaciens after sea bathing. A 13-year-old boy was treated for otitis media since he was approximately 4-years-old. On June 15, 20XX, he swam in the sea, and a week later, he complained of pain in the left year; he then consulted a family doctor. He was treated with antimicrobial agents by both oral and intravenous infusion and also with left myringotomy twice, ventilation tube therapy, and ear drops of OFLX. However, his condition did not improve. We suggested the destruction of auditory ossicles using CT on July 30, 20XX. S. putrefaciens was detected from the bacterial culture examination of the left otorrhea. He was then referred to our hospital for surgery on August 5, 20XX. We suspected otogenic complications as the antimicrobial agents did not work and cholesteatoma because CT revealed shadows in the middle ear cavity. We then performed an emergency surgery on the same day and found that a granuloma filled the mastoid antrum and that cholesteatoma spread from the epitympanum through the mastoid antrum inlet. Post surgery, he was treated with CPFX by intravenous infusion for 8 days; his condition improved and he was discharged. These results suggest that cholesteatoma should be considered in patients with otitis media who show resistance to antimicrobial agents. Furthermore, surgery should be considered to investigate the CT or local findings.
