Peripheral ulcerative keratitis secondary to chronic Citrobacter koseri canaliculitis

Citrobacter koseri is a rarely reported ocular pathogen. It may induce severe peripheral corneal inflammation and subsequent perforation by canaliculitis. Timely detection of the reservoir of this pathogen would halt its progression. The purpose of this study was to report a rare presentation of C. koseri chronic canaliculitis complicated with perforating peripheral ulcerative keratitis (PUK). A 71-year-old female who had several episodes of C. koseri conjunctivitis in the past 6 months was admitted to our infection ward under the impression of fever that was suspected to be related to urinary tract infection. She had concurrent copious mucopurulent discharge and blurred vision. Ocular examination disclosed hyperemic conjunctiva and an oval-shaped corneal infiltrate at 5-6 o'c periphery, which later rapidly progressed to PUK and corneal perforation. Despite aggressive treatment, the cornea continued to thin, and a second perforation occurred. After meticulous examination of the ocular adnexa, irrigation of inferior canaliculi revealed pustular discharge with profuse concretions indicating chronic canaliculitis. A cutaneous-lacrimal fistula was also found. Frequent antibiotic irrigation of the canaliculus finally halted the corneal melting and the cornea healed. Although rare, C. koseri may not only cause chronic canaliculitis but also induce peripheral corneal inflammation mimicking autoimmune-related PUK. Identification of C. koseri from conjunctival swab cultures should prompt the physicians to check chronic persistent canaliculus infections, which may help prevent rapidly progressive corneal inflammation and thus perforation. Management of C. koseri canaliculitis-induced PUK must also include antibiotic irrigation to eradicate canaliculitis infection at the reservoir and not just topical antibiotics.