Acute keratoconjunctivitis due to contamination of contact lens care solution with histamine-producing Raoultella species: A case report

RATIONALE: Contact lens storage cases are known to be contaminated by a significant number of bacteria. However, histamine-producing Raoultella species has not been reported to contaminate contact lens storage case. PATIENT CONCERNS: A 27-year-old woman with keratoconjunctivitis that developed in the left eye owing to a cosmetic contact lens and poor hygiene was referred to our hospital. The corrected visual acuity was hand motion. DIAGNOSES: Corneal infection other than Acanthamoeba keratitis (AK) and corneal hypoxia were excluded. INTERVENTIONS: We initiated empirical therapy for AK, although no cysts or trophozoites were detected in the cornea and in the lens care solution. Analysis of 16S rDNA sequences from the lens care solution yielded the highest homology with Raoultella species, which are histamine-producing bacteria. Histamine was estimated to be 492 ng/mL in the lens care solution. OUTCOMES: Her clinical course was distinct from that of usual AK cases. The corrected visual acuity increased up to (1.2) only 5 days after initiating empirical therapy. LESSONS: To our knowledge, this is the first report to indicate an association between histamine-producing bacteria and keratoconjunctivitis. We should pay an attention to the microbial contamination of contact lens storage cases by histamine producing bacteria.