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Importance: Evaluation of the microbiological diagnostic profile of multidrug-resistant Pseudomonas aeruginosa keratitis and potential management with rose bengal-photodynamic antimicrobial therapy (RB-PDAT) is important., Objective: To document the disease progression of carbapenemase-resistant P aeruginosa keratitis after an artificial tear contamination outbreak., Design, Setting, and Participants: This retrospective observation case series included 9 patients 40 years or older who presented at Bascom Palmer Eye Institute and had positive test results for multidrug-resistant P aeruginosa keratitis between January 1, 2022, and October 31, 2023., Main Outcomes and Measures: Evaluation of type III secretion phenotype, carbapenemase-resistance genes blaGES and blaVIM susceptibility to antibiotics, and in vitro and in vivo outcomes of RB-PDAT against multidrug-resistant P aeruginosa keratitis., Results: Among the 9 patients included in the analysis (5 women and 4 men; mean [SD] age, 73.4 [14.0] years), all samples tested positive for exoU and carbapenemase-resistant blaVIM and blaGES genes. Additionally, isolates were resistant to carbapenems as indicated by minimum inhibitory concentration testing. In vitro efficacy of RB-PDAT indicated its potential application for treating recalcitrant cases. These cases highlight the rapid progression and challenging management of multidrug-resistant P aeruginosa. Two patients were treated with RB-PDAT as an adjuvant to antibiotic therapy and had improved visual outcomes., Conclusions and Relevance: This case series highlights the concerning progression in resistance and virulence of P aeruginosa and emphasizes the need to explore alternative therapies like RB-PDAT that have broad coverage and no known antibiotic resistance. The findings support further investigation into the potential effects of RB-PDAT for other multidrug-resistant microbes.

Purpose: To evaluate the in vivo corneal changes after Rose Bengal photodynamic antimicrobial therapy (RB-PDAT) treatment in New Zealand White rabbits., Methods: Sixteen rabbits were divided into 5 groups. All groups underwent deepithelialization of an 8 mm diameter area in the central cornea. Group 1: balanced salt solution drops only, group 2: 0.2% RB only, group 3: green light exposure (525 nm, 5.4 J/cm2) only, group 4: 0.1% RB-PDAT, and group 5: 0.1% RB-PDAT. All rabbits were followed clinically. Group 5 rabbits were followed using anterior segment optical coherence tomography (AS-OCT) and clinically. On day 35 after initial treatment, 1 rabbit from group 5 was re-exposed to green light (5.4 J/cm2) to evaluate reactivation of the remaining RB dye, and terminal deoxynucleotyl transferase-mediated UTP-biotin-nick-end labeling assay was performed on corneal cryosections., Results: Complete reepithelization was observed, and corneas remained clear after treatment in all groups. In group 5, AS-OCT revealed a cross-linking demarcation line. AS-OCT showed RB fluorescence and collagen cross-linking in all treated eyes of group 5 animals after 5 weeks of treatment. Photobleached RB retention in the corneal stroma was corroborated by fluorescence confocal microscopy on frozen sections. There was no evidence of a sustained cytotoxic effect through terminal deoxynucleotyl transferase-mediated UTP-biotin-nick-end labeling at 5 weeks., Conclusions: RB-PDAT with 0.1% RB is a safe procedure. There was no difference clinically and on histopathology compared with control groups. In eyes where RB dye is retained in the corneal stroma after 1 month of treatment, oxidative stress is not evidenced at long term., Competing Interests: A. Arboleda, H. Durkee, M. C. Aguilar, D. Miller, G. Amescua, and J.-M. Parel are listed inventors on a provisional patent application on the PDAT instrument submitted by and assigned to the University of Miami. The remaining authors have no funding or conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose : To identify interventional factors associated with improved visual results and faster time to resolution for patients with Pseudomonas scleritis. Methods : Retrospective study analyzing inciting factors, therapeutic modalities, and outcomes of patients with Pseudomonas scleritis. Results : A total of 24 patients were analyzed; 22 were treated as outpatients. All had resolution of infection and 58% ( n  = 14) maintained ≥20/200 vision. Medical therapy included topical and oral antibiotics; seven received additional subconjunctival injections; two were admitted for IV antibiotics. Patients presenting with ≥20/200 vision were more likely to maintain this level of vision ( n  = 8, 80%) compared to those presenting with severe vision loss ( n  = 5, 36%) ( p  = 0.04). A similar proportion of patients who received ( n  = 8, 61%) and did not receive ( n  = 5, 39%) oral steroids achieved 20/200 vision or better once infection resolved, p  = 1.0. Conclusions: Pseudomonas scleritis can be successfully managed in the outpatient setting. Oral steroids do not appear harmful in the treatment of this disease.

Purpose: To describe 2 cases of Nocardia keratitis resistant to topical compounded amikacin therapy., Methods: A 24-year-old woman presented with a corneal infiltrate. Cultures were taken, and topical moxifloxacin was administered. Corneal biopsy was performed when clinical status deteriorated, which confirmed infection with Nocardia. The patient was administered topical compounded amikacin. When clinical status further deteriorated, she was switched to compounded trimethoprim-sulfamethoxazole, which resulted in rapid resolution. Separately, a 22-year-old woman presented with contact lens-related keratitis that grew Nocardia asteroides. Corneal cultures and drug sensitivity testing revealed a strain of N. asteroides resistant to amikacin and imipenem, but sensitive to tobramycin. After a protracted clinical course, the keratitis ultimately responded to topical tobramycin leaving the patient with a pericentral corneal scar., Conclusions: Nocardia keratitis is an atypical infection for which standard management algorithms exist. However, atypical cases require that these patients be followed closely for the response to therapy.