Corynebacterium propinquum Keratitis Identified Using MALDI-TOF

Purpose:To report a corneal infection due to Corynebacterium propinquum identified using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) method.Methods:A 94-year-old woman presented with suppurative keratitis. Her ocular history included Fuchs corneal dystrophy, corneal transplantation, and glaucoma. A gram-stained smear revealed coryneforms. Colonies on bacterial culture media were assayed by MALDI-TOF.Results:Identification of C. propinquum was confirmed by RNA polymerase subunit (rpoB) gene sequencing. The patient was treated with topical cefazolin, gentamicin, and fluorometholone, and her vision improved to 20/160 unaided when last seen.Conclusions:MALDI-TOF can correctly identify isolates that are both uncommon and difficult to distinguish from related species. The ease and low running costs of this method will improve the laboratory diagnosis of ocular infections.