Study examines diagnosis, treatment of Acanthamoeba keratitis, concomitant infections

Am J Ophthalmol. 2009;148(1):13-19.

Patients with Acanthamoeba keratitis who develop infectious crystalline keratopathy are prone to acute pain and severe epithelial damage, a study showed.

"Combined [Acanthamoeba keratitis] and [infectious crystalline keratopathy] may exhibit increased pathogenicity with the onset of severe, often new, pain and acceleration of localized tissue loss and resultant scarring," the study authors said.

The retrospective study included 111 patients diagnosed with Acanthamoeba keratitis and infectious keratitis. Of five Acanthamoeba keratitis patients with evidence of additional bacterial keratitis, infectious crystalline keratopathy developed in three patients. Two patients had negative bacterial cultures at the time of their Acanthamoeba keratitis diagnoses but later tested positive for Streptococcus oralis. The third patient, who had undergone partial antibiotic treatment, tested positive for mild methicillin-sensitive Staphylococcus aureus.

Two patients received topical corticosteroids before Acanthamoeba keratitis diagnosis; one patient received topical corticosteroids after diagnosis.

All infections resolved with medical treatment alone. However, clinicians should consider Acanthamoeba coinfection and endosymbiosis when evaluating Acanthamoeba keratitis management, particularly in atypical cases.

"Further research is needed to understand the precise mechanism of the introduction of coinfectious pathogens and their role in the pathogenicity of [Acanthamoeba keratitis]," the authors said.