Molecular and Histopathologic Correlation Between Acanthamoeba Species Recovered from Patients Who Underwent Therapeutic and Optical Penetrating Keratoplasties After Rose Bengal Photodynamic Antimicrobial Therapy
Sara Mustafa1, Paula A. Sepulveda-Beltran1,2,3, Yoseph Sayegh4, Harry W. Flynn Jr1, Darlene Miller3, Sander Dubovy1,4,
Guillermo Amescua1, Jean-Marie Parel1,2, Jaime D. Martinez1
1Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida; 2Ophthalmic Biophysics Center, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida;
3Ocular Microbiology Laboratory, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida; 4Florida Lions Ocular Pathology Laboratory, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
Purpose: To compare the genotypic profile and histopathology of Acanthamoeba isolates recovered from patients who underwent Therapeutic Penetrating Keratoplasties (TPK), and Optical Penetrating Keratoplasties (OPK) after adjunct treatment with Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT).
Methods: Retrospective review of patients diagnosed with Acanthamoeba keratitis at the Bascom Palmer Eye Institute between August 2016 and August 2022, that underwent TPKs and OPKs after RB-PDAT. Of patients with Acanthamoeba keratitis that received RB-PDAT (n=39), 17 met inclusion criteria. Treatment success was defined as resolution of the infiltrate and treatment with OPK for visual improvement. RB-PDT treatment failure was defined as undergoing TPK for treatment of the infection. Host corneas were analyzed after keratoplasty for residual microbes, Acanthamoeba resistance to standard medical treatment (SMT), presence and grading of the number of cysts, and cyst depth.
Results: 17 eyes of 17 patients were included (43.7±19.9 years old; 70.5% female). Mean follow-up time was 37.6±19.1 months. Of those, 9 patients (52.9%) required TPKs, and 8 (47.0%) underwent OPKs. Risk factors included contact lens use (88.2%), topical steroid use (52.9%). Cultures were positive in 11 patients (65%), 3 (17%) required corneal biopsies, and 3 (17%) were positive after staining of the corneal scraping. Of patients that underwent TPK, 3 (33%) required ≥2 PDATs, 6 (67%) received additional treatment with oral Miltefosine and 2 (25%) presented clear grafts at one year. Comparatively, in the OPK group, 6 (35%) patients required ≥2 RB-PDATs, 2 (25%) received additional treatment with oral Miltefosine and 8 (89%) presented clear grafts at one year. Results of residual microbes, cyst number and depth on host corneas and microbial resistance to standard medical treatments are pending.
Conclusions: Acanthamoeba isolates recovered from patients in South Florida may have increased resistance to SMT contributing to RB-PDT treatment failure with resulting TPK. Further studies are required to determine the association between these findings and the resistance to the current therapies available.