Therapeutic Penetrating Keratoplasty In Advanced Polymicrobial Keratitis Caused By Acanthamoeba And Pseudomonas Aeruginosa

To describe the clinical course and surgical management of advanced corneal destruction caused by polymicrobial keratitis involving Acanthamoeba and Gram-negative bacterial infection in a contact lens wearer.

Tertiary referral ophthalmology center with specialized corneal and transplant services.

A 27-year-old female hairdresser and monthly contact lens user presented with acute ocular pain, photophobia, and significant visual reduction to 20/200 of two days’ duration. Slit-lamp examination revealed a central corneal ulcer with stromal necrosis, epithelial defect, hypopyon, and diffuse edema. Polymicrobial infection was suspected. Corneal scrapings and contact lenses were submitted for microbiological culture and PCR testing. Intensive topical and systemic antimicrobial therapy was initiated. Cultures grew Pseudomonas aeruginosa. Although PCR for Acanthamoeba was negative, in vivo confocal microscopy demonstrated characteristic cystic structures, prompting initiation of anti-amoebic treatment.

Initial therapy halted rapid stromal progression; however, persistent amoebic infection led to a chronic non-healing epithelial defect with progressive corneal neovascularization. After 2.5 months of intensive medical treatment without meaningful structural recovery, therapeutic penetrating keratoplasty was performed. Postoperatively, serial intrastromal/subconjunctival bevacizumab injections were administered to control corneal neovascularization. Infection resolved completely, visual acuity improved steadily to 20/25 and corneal surface stability was restored.

Polymicrobial keratitis involving Acanthamoeba and Gram-negative bacteria may exhibit prolonged, treatment-resistant behavior with progressive structural compromise. When maximal medical therapy fails, therapeutic penetrating keratoplasty provides definitive eradication of infection and restoration of ocular integrity. Adjunctive anti-VEGF therapy may be selectively considered to control corneal neovascularization and optimize graft prognosis without compromising infection control.