A case of bacterial keratitis caused by multi-drug-resistant Shewanella algae without marine exposure
A 66-year-old man was sent to the emergency department from a nursing hospital because of desaturation. He had been hospitalized for more than 2 years in an unconscious state due to a cervical spine injury. He was unable to close his eyes voluntarily. Neither the patient nor his family had a history of marine exposure. At admission, pneumonia was suspected, and conjunctival injection, purulent discharge and central white opacity were detected in his right eye. He was admitted to the respiratory department, and treatment with piperacillin–tazobactam was started for pneumonia. An ophthalmologist examined the patient at the bedside. Examination of his right eye revealed 6.0 × 5.0 mm corneal opacity and hyphema with hypopyon in the anterior chamber. Fundus examination was impossible due to corneal haziness. Corneal swabs were sent for Gram staining, bacterial culture and antimicrobial sensitivity testing, KOH mount smear and fungal culture. Empirical treatment with tobramycin, moxifloxacin and ofloxacin eye drops was started. The KOH smear and Gram stain were negative. After a 2-day incubation, medium-sized gray and dark pink colonies grew on blood agar plate and chocolate agar plate (). Other types of colony did not grow on the plate. S. algae was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using the Vitek system (bioMérieux, Marcy-L’Étoile, France). 16S rRNA sequencing revealed 99.93% (1410/1411 bp) identity with S. algae JCM 21037(T) (GenBank accession number ). Susceptibility testing of the isolate indicated susceptible to amikacin, aztreonam, cefepime, ceftazidime, colistin and gentamicin, resistant to cefotaxime, imipenem, piperacillin and piperacillin/tazobactam, and intermediate to ciprofloxacin, levofloxacin and meropenem. We added steroid eye drops to control the inflammation and continued the antibiotic eye drops. After 14 days, his keratitis had improved.