Eye-banking risk factors for fungal endophthalmitis compared with bacterial endophthalmitis after corneal transplantation

Safety and efficacy of McCarey-Kaufman medium supplemented with colistin (polymyxin E) and amphotericin B in inhibiting the multidrug-resistant Pseudomonas aeruginosa using an ex vivo donor corneal infection model

PURPOSE

This study aimed to evaluate the efficacy and safety of McCarey-Kaufman (MK) medium supplemented with colistin and amphotericin B in inhibiting the growth of multidrug-resistant Pseudomonas (P.) aeruginosa , using an ex vivo experimental model with human donor corneas.

METHODS

Cadaveric human corneas deemed unsuitable for corneal transplantation were obtained, and MK media were supplemented with colistin and amphotericin B. Multidrug-resistant P. aeruginosa was cultured and used to infect the human donor corneas ex vivo . Infected corneas were placed in the MK media with additional antibiotics (colistin and amphotericin B) and the standard MK media, which served as the control arm for comparison. Corneal opacity due to infiltration and quantitative analysis of colony-forming units (CFUs) were assessed. The viability of the corneal endothelium was assessed using trypan blue staining.

RESULTS

Corneas incubated in MK media supplemented with additional antibiotics showed less corneal opacification compared with those in standard MK media at both 48- and 96-hour (hr) time points. Quantitative analysis revealed a lower bacterial load and a significant reduction in CFU in the corneas incubated in MK media with additional antibiotics compared with the control group. At 48 hrs, there was 84% ( P value = 0.024) reduction in bacterial load, and at 96 hr, a 53% ( P value = 0.016) reduction was observed in comparison with those placed in standard MK media. The trypan blue staining tests revealed that the extent of endothelial cell loss in corneas incubated in supplemented MK media was comparable to the ones in standard MK media.

CONCLUSION

The addition of colistin and amphotericin B to MK media demonstrated efficacy in inhibiting the growth of multidrug-resistant P. aeruginosa in an ex vivo cornea infection model. The supplemented media had no detrimental effect on the corneal endothelium. The findings suggest that supplementing the MK media with these broad-spectrum antimicrobial agents may help mitigate the risk of postoperative donor-related infection in the recipients by reducing and containing the load of microbial contamination in donor corneas.

Anti-fungal efficacy of combination of amphotericin B with colistin and gentamicin in McCarey-Kaufman corneal preservation medium

Purpose

To curtail the potential of donor corneal tissue disseminating fungi to the recipient's eye, we evaluated the addition of amphotericin B to McCarey-Kaufman (M-K)-corneal storage medium supplemented with colistin.

Methods

Amphotericin B was examined for its ability to inhibit the growth of Candida albicans and Aspergillus flavus using a microbroth dilution test and checkerboard assay in combination with only gentamicin and a combination of colistin, gentamicin, and amphotericin B. The safety on epithelium and endothelium was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Results

The minimal inhibitory concentration of gentamicin was found to be >256 μg/ml against both C. albicans and A. flavus, whereas that of amphotericin B was found to be in a range of 0.25-0.5 and 1-2 μg/ml for C. albicans and A. flavus, respectively. According to the checkerboard assay, 80% (4/5) of C. albicans isolates and 100% (5/5) of A. flavus isolates responded synergistically to the combination of amphotericin B and gentamicin, but only 20% (1/5) of C. albicans isolates showed an additive effect. None of the tested isolates displayed antagonism. The combined effect of the three drugs also did not display any antagonistic effect. Additionally, the MTT assay reveals no toxic effect of the antimicrobials used on corneal epithelial and endothelial cells.

Conclusion

In vitro experiments demonstrate that amphotericin B is not toxic to either epithelium or endothelium and is a promising additive to the M-K medium supplemented with colistin.

Keratoplasty Registries: Lessons Learned

ABSTRACT

Clinical registries have been developed for decades in the field of ophthalmology, and they are especially well-suited to the study of keratoplasty practices. A comprehensive donor/recipient registry system can provide insight into donor, recipient, and surgical factors associated with immediate and long-term outcomes and adverse reactions. Furthermore, linkage with demographic databases can elucidate relationships with social determinants of health and potentially shape public policy. The vast sample size and multicenter nature of registries enable researchers to conduct sophisticated multivariate or multilayered analyses. In this review, we aim to emphasize the importance of registry data for keratoplasty practice and 1) summarize the structure of current keratoplasty registries; 2) examine the features and scientific contributions of the registries from Australia, the United Kingdom, Singapore, the Netherlands, Sweden, Eye Bank Association of America, and European Cornea and Cell Transplant registries; 3) compare registry-based studies with large single-site clinical studies; 4) compare registry-based studies with randomized control studies; and 5) make recommendations for future development of keratoplasty registries. Keratoplasty registries have increased our knowledge of corneal transplant practices and their outcomes. Future keratoplasty registry-based studies may be further strengthened by record linkage, data sharing, and international collaboration.

Toxicity of Amphotericin B in Rabbit Corneal Epithelial Cells Stored in Optisol™-GS: Corneal Epithelial Cell Morphology and Migration

PURPOSE

To evaluate the toxicity of Amphotericin B (AmB) in Optisol™-GS Corneal Storage Media (Bausch & Lomb) on corneal epithelial cell (CEC) morphology and migration ability.

METHODS

Sclerocorneal strips were removed from male Japanese white rabbits, and then stored at 4 °C in Optisol™-GS containing 0 µg/ml of AmB (control group) and 2.5, 5, 25, and 50 µg/ml of AmB (AmB groups; four eyes per group). After 7 days of storage, CEC morphology was evaluated by hematoxylin-eosin staining, immunohistochemical staining (ZO-1), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Moreover, to evaluate CEC migration ability, three corneal blocks (6-8 × 3 mm each) from one preserved cornea were cultured for 24 h, and the area of CEC migration (2 mm at the central region) onto the stromal surface was then measured.

RESULTS

At 5, 25, and 50 µg/ml of AmB, deformation and vacuolation of CECs were observed in all preserved corneas. ZO-1 expression was significantly reduced in corneas preserved at AmB concentrations of 25 and 50 µg/ml. TUNEL Labeling Index was significantly increased at AmB concentrations of ≥5 µg/ml. CEC migration was inhibited in a dose-dependent manner at AmB concentrations of 25 and 50 µg/ml compared to the control group.

CONCLUSIONS

The addition of AmB to Optisol™-GS can be toxic to CECs and inhibit their migration at a concentration of ≥5 µg/ml. AmB at a concentration of 2.5 µg/ml can be considered safe for the preservation of donor corneal tissue used in corneal epithelial transplantation surgery.

Overview of Short-Term and Intermediate-Term Corneal Storage Solution: Comparison of Clinical Outcomes and Need For Future Research

ABSTRACT

Corneal donor tissue preservation techniques have incrementally improved since the introduction of McCarey-Kaufman storage solution from short-term storage to intermediate duration of storage with the advent of organ culture and Optisol GS storage solutions. Improved understanding of the corneal endothelial cell physiology has helped in designing newer storage solutions, such as the Life 4C and Cornea Cold. The incorporation of antibiotics, ATP precursors, minerals, and vitamins has improved the viability of tissues. In addition, these modifications to the newer storage solutions have increased the endothelial longevity and metabolic activity. Despite these advances, the duration of tissue storage has largely been restricted to 2 weeks in Optisol GS and 4 weeks in organ culture. The role and cost-effectiveness of antifungal supplementation and the need for improved epithelial preservation are additional areas that need to be explored. This review intends to summarize the efficacy and viability of donor corneas in different tissue storage solution and compare clinical outcomes while providing an insight into the challenges in developing newer methods of corneal preservation.

Endophthalmitis secondary to donor to host infection in posterior lamellar keratoplasties: A systematic review

Donor to host transmission of infectious agents is a well-recognized entity, more commonly related to Endothelial Keratoplasty (EK) than to Penetrating Keratoplasty (PK), that involves complications ranging from interface keratitis to endophthalmitis. A systematic review of the literature was conducted to identify the published articles until December 2020 reporting cases of endophthalmitis secondary to corneal graft contamination in posterior lamellar keratoplasties (DSAEK and DMEK) along with donor characteristics, microbiological profile, treatment and outcomes. Each identified article was assessed to meet donor to host infection criteria, defined as a post-procedural infection in which the same microbiological agent was identified in both the donor corneoscleral rim or preservation medium and receptor ocular tissue. From 23 research articles, eight reports of endophthalmitis in nine patients following DSAEK or DMEK secondary to donor to host infection fulfilled the inclusion criteria. The majority were male and the median age was 72.0 (45.0-81.0) years old. Indications of surgery were primarily pseudophakic bullous keratopathy and Fuchs dystrophy. A fungal pathogen was identified in eight of nine patients. All the cases underwent surgical management with lenticule removal or endothelial plaque aspiration. The final corrected distance visual acuity (CDVA) in all cases was 20/200 or better. Endophthalmitis after an EK procedure is a rare complication whose outcome depends on the aggressive and precocious treatment. Identification of early signs of interface keratitis and lenticule removal seems mandatory in patients undergoing DSAEK or DMEK to prevent further involvement of the globe.

Killing efficacy of a new hypothermic corneal storage medium against the micro-organisms frequently found in human donor cornea intended for transplantation

Objective

To study the in vitro killing efficacy of Kerasave (AL.CHI.MI.A Srl), a medium provided with amphotericin B tablet for hypothermic storage of human donor corneas, against relevant contaminants associated with postkeratoplasty infections.

Methods and Analysis

The antimicrobial activity of Kerasave was determined after 0, 3 and 14 days of incubation at 2°C-8°C, inoculating Kerasave and the control medium with 10⁵-10⁶ colony forming units (CFU) of Candida albicans (CA), Fusarium solani (FS), Aspergillus brasiliensis (AB), Staphylococcus aureus (SA), Enterococcus faecalis (EF), Bacillus subtilis spizizenii (BS), Pseudomonas aeruginosa (PA), Enterobacter cloacae (EC) and Klebsiella pneumoniae (KP). Log₁₀ reductions at different time intervals were determined by assessing the number of viable CFU using the serial dilution plating technique.

Results

After 3 days, Kerasave induced the highest log₁₀ decrease in the concentrations of KP, PA, CA and EC (5.37, 4.15, 2.97 and 2.67, respectively; all p<0.001). The log₁₀ decreases of SA and EF were 2.27 and 2.11, respectively (all p<0.001). The lowest log₁₀ decrease was observed in BS, AB and FS concentrations (0.25, 0.30 and 0.67, respectively; p<0.001 for BS and AB and p=0.004 for FS). After 14 days, the microbial count of CA, FS, SA, EF, PA and EC further decreased (p=0.006 for FS; p<0.001 for the others).

Conclusion

Kerasave effectively reduced or kept unchanged the microbial concentration of almost all tested strains after 3 days. Thus, this novel medium represents a valuable tool to control the microbial contamination of human donor corneas during hypothermic storage for up to 14 days before transplantation.

Distribution, Prevalence, and Causative Agents of Fungal Keratitis: A Systematic Review and Meta-Analysis (1990 to 2020)

Objectives

This study aims to provide an overview of the prevalence, distribution, and causative agents of fungal keratitis.

Methods

All the articles with data on the prevalence of fungal keratitis among various patient groups from January 1, 1990 to May 27, 2020 were retrieved through a systematic search in PubMed, Scopus, Web of Science, and Google Scholar. Data were extracted, and the pooled estimated prevalence of fungal keratitis, yeast/mold infection, the spectrum and frequency of various causative agents, and the pooled estimated prevalence of mixed infections were calculated in general and in various countries (wherever possible) using meta-analysis.

Results

From 11,235 articles retrieved in the primary search step, 169 met the inclusion criteria. The 169 eligible articles were divided into six groups and analyzed separately. The pooled prevalence of fungal keratitis was variable with values ranging from 0.05% among postkeratoplasty patients to 43.01% among patients with a clinical suspicion of fungal keratitis. There was also a country-dependent variation in the prevalence (Paraguay: 50.1% (95% CI, 35.11, 65.00); Ireland: 1.1% (95% CI, 0.03, 6.04)). Except for postkeratoplasty cases (yeast: 51.80%), in all patient groups, molds were more common than yeasts. Although more than 50 distinct species of fungi have been found to cause fungal keratitis, Fusarium species followed by Aspergillus species were the most common causes of the disease. In general, 9.29% (95% CI, 6.52, 12.38) of fungal keratitis cases were mixed with bacterial agents.

Conclusion

The prevalence of fungal keratitis can vary dramatically depending on the patient groups and geographical origin; however, the dominant causative agents are generally similar.

Incidence of Fungal Infection in Positive Donor Rim Cultures after Corneal Transplantation

PURPOSE

To determine the clinical outcomes of corneal transplant patients that had positive rim cultures for fungi.

METHODS

Retrospective study.

RESULTS

Of 1276 rim cultures obtained between 2009 and 2019, 16 were positive for fungus (incidence of 1.25%). Clinical data were available for 12 patients. Candida and Cladosporium species were the most common organisms. Recipient ages ranged from 51 to 86 (median age 69 years; 9 males, 7 females). The most common surgery was Endothelial Keratoplasty (n = 8). There were no instances of fungal keratitis or endophthalmitis. Three patients were treated with prophylactic antimycotics. One patient developed bacterial keratitis. One patient had a varicella zoster virus reactivation without corneal involvement.

CONCLUSIONS

This study adds to the growing data on the low rate of fungal keratitis and endophthalmitis after a corneal transplant, even in the case of positive rim cultures. This study also suggests that positive rim cultures do not advance the risk of postoperative fungal infection in the recipient.

A Cluster of Corneal Donor Rim Cultures Positive for Achromobacter Species Associated With Contaminated Eye Solution

PURPOSE

To investigate a cluster of corneoscleral rim cultures positive for Achromobacter species over a 6-month period at Massachusetts Eye and Ear.

METHODS

An increased rate of positive corneal donor rim cultures was noted at Massachusetts Eye and Ear between July and December 2017. Positive cultures were subjected to identification and antimicrobial susceptibility testing by phenotypic (MicroScan WalkAway) and genotypic (16S rDNA sequencing) methods. Samples of the eye wash solution (GeriCare) used in the eye bank were also evaluated. Antimicrobial activity of Optical-GS against Achromobacter spp. at 4°C and 37°C was assessed by time-kill kinetics assay.

RESULTS

Of 99 donor rims cultured, 14 (14.1%) grew bacteria with 11 (78.6%) due to uncommon nonfermenting Gram-negative bacilli. These had been identified by standard automated methods as Achromobacter (n = 3), Alcaligenes (n = 3), Ralstonia (n = 2), Pseudomonas (n = 2), and Stenotrophomonas (n = 1). Eight of these 11 isolates were subsequently available for molecular identification, and all were identified as Achromobacter spp. Six bottles of eyewash solution were evaluated and were positive for abundant Achromobacter spp. (3.4 × 105 ± 1.1 CFU/mL). Optisol-GS had no bactericidal activity against Achromobacter spp. at 4°C after 24-hour incubation but was bactericidal at 37°C. None of the patients who had received the contaminated corneas developed postoperative infection.

CONCLUSIONS

An eyewash solution arising from a single lot was implicated in the contamination of donor rims by Achromobacter spp. The isolates were able to survive in the Optisol-GS medium at the recommended storage temperature. This highlights the need to continue improving protocols for tissue preparation and storage.

Eye bank and theatre factors for positive microbiological culture of corneoscleral rim and cornea storage medium in the real-world

OBJECTIVES

To evaluate microbiological culture rate and positivity of corneoscleral rim and cornea storage media as well as possible risk factors for contamination with real-world data.

METHODS

Data of consecutive cornea donors implanted in the reference centre from January 2013 to January 2018 were reviewed. Information about cornea characteristics (donor demographic data, endothelial cell density, type of cornea conservation, days of storage, and precut vs full-thickness tissue), and microbiological culture information (corneoscleral rim vs storage sample, positive result) were statistically analysed.

RESULTS

During the study period, 1369 corneas (737 donors) were implanted. Cultures were performed in 76.8% (n = 1052) of them and were positive in 3.2% of cases, mainly bacteria (84.4%). Corneas preserved in hypothermia represented 61.8% of all positive microbiology results (p < 0.001). Other analysed risk factors did not reach statistically significant association with microbiological positivity. None of the 34 cases with positive microbiological cultures reported ocular infection for the recipients in at least 6 months' follow-up.

CONCLUSIONS

Microbiological tests rate in real-world practice are high despite not being compulsory. Organotypic cultured corneas showed a statistically less positivity in corneoscleral and storage medium than hypothermic ones, resulting in another advantage of this kind of cornea storage. Although precut corneas are thought to present less microbiological positivity, a statistically significant association was not found in the present study.

Incidence and outcome of transplantation of fungal-culture-positive donor corneoscleral tissue in optical keratoplasty

PURPOSE

This study aims to determine the incidence of fungal-culture-positive corneoscleral donor rim in patients undergoing keratoplasty and evaluate clinical outcomes of eyes that received these contaminated donor tissues.

METHODS

Patients who had optical keratoplasty between 2006 and 2016 and were found to have fungal-culture-positive donor rim were included. Microbiological and eye bank records were reviewed to determine the incidence of positive fungal rim cultures. Data were collected on visual and clinical outcomes. The main outcome measures were fungal-culture-positive donor rim and development of fungal keratitis or endophthalmitis post keratoplasty. Long-term clinical outcome and associated complications were the secondary outcome measures.

RESULTS

Out of 9620 cases of corneal transplants, 145 (1.5%) had fungal-culture-positive donor rim. Candida was the most common organism, cultured in 127 (87.6%) cases. There were no cases of postoperative fungal keratitis or endophthalmitis. Median follow-up was 4.8 years (interquartile range 3.8-7.2 years). Only eight cases (5.5%) received prophylactic antifungal treatment. There were 34 (23.4%) cases of rejection, 13 (8.9%) developed glaucoma, and 7 (4.8%) developed late bacterial keratitis. At last follow-up, best corrected visual acuity was 20/60 or better in 88 cases (60.7%) and 115 eyes (79.3%) had a clear graft.

CONCLUSION

The incidence of fungal-culture-positive donor rim is extremely low. The risk of developing fungal keratitis or endophthalmitis in patients who received contaminated donor tissue was almost negligible. Further studies are warranted to prove whether prophylaxis or adding amphotericin B in Optisol-GS confers any added benefit.

Infectious keratitis after lamellar keratoplasty

Infectious keratitis after lamellar keratoplasty is a potentially devastating complication that may severely limit the visual and anatomical outcomes. The deep-seated location of the infiltrates, sequestration of the pathogenic microorganisms and limited penetration of the currently available antimicrobial agents often results in delayed diagnosis that may jeopardize the management in these cases. Fungal keratitis is more common as compared with bacterial or viral keratitis and classically presents as white interface infiltrates that may not be associated with significant inflammation. Confocal microscopy may help to establish a rapid diagnosis in such cases, and anterior segment optical coherence tomography may be used to determine the extent of infection and monitor its progression. Conservative measures such as topical antimicrobials and interface irrigation with antimicrobial agents may be done. Surgical intervention in the form of partial excision/removal of the graft in endothelial keratoplasty or a full-thickness keratoplasty is often required for the effective management of deep-seated infections. Timely diagnosis and intervention may result in complete resolution of infection in both anterior lamellar and endothelial keratoplasty. Infections after anterior lamellar keratoplasty have a fair prognosis, and a clear graft with functional visual acuity may be achieved in most cases. By contrast, infections after endothelial keratoplasty have a guarded prognosis, and the presence of concomitant endophthalmitis may further complicate the graft survival and visual outcomes.

Distribution of Microbial Keratitis After Penetrating Keratoplasty According to Early and Late Postoperative Periods

Objectives:

The aim of this study was to investigate the distribution of microbial agents in the early and late postoperative periods in patients with microbial keratitis (MK) after penetrating keratoplasty (PK).

Materials and Methods:

The records of 36 patients who were clinically diagnosed as having MK after PK were retrospectively reviewed. Culture results were obtained from microbiology records and the organisms that were produced were noted. A case was deemed as viral keratitis based on the clinical appearance, negative cultures, and response to antiviral treatment. Keratitis development times were evaluated in 2 categories: early (within the first year) and late (after year 1) postoperative period. Mann-Whitney U and Kruskal-Wallis tests were used to compare numerical variables that did not show normal distribution and chi-square test was used to compare categorical variables.

Results:

The majority of MK cases were of bacterial origin (55.5%, n=20), followed by viral (41.7%, n=15) and fungal (2.8%, n=1). Of the 15 cases of early postoperative MK, 10 were bacterial, 4 were viral, and 1 was fungal; however, among cases of late postoperative MK, 10 were bacterial and 11 were viral. The majority (65%) of early and late bacterial infections were caused by gram-positive strains (most commonly staphylococci). Gram-positive bacteria caused keratitis significantly earlier than gram-negative bacteria (p=0.037). Viral and gram-negative bacterial MK was more frequent in the late postoperative period, but the difference was not statistically significant.

Conclusion:

In our study, bacterial keratitis was more common in post-keratoplasty MK than viral and fungal keratitis. Gram-positive bacteria were the most common causative agents. The increased incidence of gram-negative bacterial agents and viral keratitis in the late postoperative period can be explained by long-term topical steroid use.

Intensive care unit time and prolonged enucleation to processing interval are associated with donor cornea contamination

PURPOSE

To determine donor cornea contamination rate and to determine factors associated with cornea contamination. To assess the effect of hospitalization, intensive care unit (ICU) time, and antibiotic use on corneal contamination rate. To determine the spectrum of the contaminating microorganisms.

METHODS

The contamination rate of 212 corneas, obtained by enucleation from April 2014 to January 2015 in a single eye bank, was assessed retrospectively according to age, sex, cause of death, systemic antibiotic use, hospitalization time, ICU time, mechanical ventilation (MV), death to enucleation interval (DEI), enucleation to processing interval (EPI), and corneal epithelial exposure grading. The relative risk (RR) and adjusted RR with a 95% confidence interval were calculated using IBM-SPSS 20.0.

RESULTS

The contamination rate was 35.6% (n = 75). On multivariate analysis, ICU stay of 4 days or longer and enucleation to processing interval (EPI) greater than 7.4 h (RR 1.58, CI 0.96-2.60, P = 0.06) were associated with donor cornea contamination. Corneal contamination risk was highest from 4 to 6 days at the ICU (RR 3.40, CI 1.54-7.51, P < 0.01) and decreased after 7 days (RR 2.22, CI 1.00-4.93, P = 0.05). Coagulase-negative Staphylococcus was the most common isolated bacteria (69.6%). The frequency of gentamicin-resistant bacteria was higher among patients who stayed 4 days or longer at the ICU.

CONCLUSION

Patients staying at the intensive care unit 4 days or longer showed increased risk of corneal contamination. This is an important result to consider further indication for cornea donation.

Efficacy of Amphotericin B in Corneal Preservation Media After Extended Frozen Storage

PURPOSE

To investigate the antimycotic activity of amphotericin B deoxycholate that has been previously frozen for 28 days before supplementation of Optisol-GS.

METHODS

Triplicate Optisol-GS samples were inoculated with 10 colony-forming units (CFU) of Candida albicans. Each set of triplicate cultures was supplemented with 2.5 μg/mL of amphotericin B that was either freshly resuspended and never frozen, frozen overnight at -20°C and thawed, or frozen at -20°C for 4 weeks and thawed. The cultures were stored at 4°C, with aliquots taken at 0, 6, 24, and 72 hours for quantification. The efficacy of each preparation of amphotericin B in reducing C. albicans growth was assessed at these time points.

RESULTS

Six hours after antifungal supplementation, there was a 1.33 log10 CFU reduction with freshly resuspended amphotericin B, compared with a 1.31 log10 reduction with amphotericin B that was frozen overnight (P = 0.20) and a 1.18 log10 reduction with amphotericin B that was frozen for 4 weeks (P = 0.05). After 72 hours, there was a 2.72 log10 CFU reduction with freshly resuspended amphotericin B, a 2.64 log10 CFU reduction with amphotericin B that was frozen overnight (P = 0.45), and a 2.18 log10 CFU reduction with amphotericin B that was frozen for 4 weeks (P = 0.05).

CONCLUSIONS

Previously frozen amphotericin B remains highly effective against C. albicans. Optisol-GS supplemented with 2.5 μg/mL amphotericin B that was frozen for 4 weeks at -20°C resulted in >90% CFU reduction by 6 hours and >99% reduction by 72 hours.

A new storage solution for the hypothermic preservation of corneal grafts: an experimental study

In this experimental study we used for the first time Tiprotec^® as a solution for corneal preservation and cold storage. We compared the resultant endothelial cell morphology and viability with this obtained after preservation of the ex-vivo corneas with both usual standard techniques: conventional cold storage (using Eusol-C) and organ culture. This prospective, in vitro, 3-armed parallel study was performed with the use of 90 porcine corneas (examined for their endothelial quality and transparency) randomly selected for preservation in three storage methods (each 30 corneas): organ culture, standard cold storage (Eusol-C) and experimental cold storage (Tiprotec^®) Endothelium cell quantity and quality as well as corneal opacification were assessed. The degree of endothelial transparency was significantly reduced over time with all preservation media, without any significant difference among the three groups at any point of time. A reduction in endothelial cell density was also observed with all three preservation media after 30 days of storage without statistically significant differences between groups. The number of hexagonal and pentagonal endothelium cells was significantly reduced overtime in all media with significantly more hexagonal and pentagonal in the organ culture group compared to the cold storage groups. We could show that the cryopreservation medium Tiprotec^®, used until now for the preservation of vascular grafts, was of similar quality compared to the medium Eusol-C for the hypothermic storage of corneal tissue for an extended period of time up to 30 days. In comparison to organic culture with culture medium KII, both Tiprotec^® and Eusol-C were found less effective in preserving endothelial cell quality, as assessed by the morphometric analysis, and viability, as assessed by the degree of vacuolization at least up to the 30th day of storage. However, both, Tiprotec^®- and Eusol-C-preserved corneas demonstrated a certain capacity to recover after their submission in organ culture.

Performance of New Hypothermic Corneal Storage Media With an Antimycotic Tablet in Comparison to Traditional Hypothermic Media During Simulated Eye Bank Processing

PURPOSE

To compare the performance of Kerasave (AL.CHI.MI.A. S.R.L., Ponte San Nicolò, Italy) containing 2.5 μg/mL of amphotericin B and Optisol-GS (Bausch & Lomb, Bridgewater, NJ) cold corneal storage media on donor corneas during routine eye bank procedures.

METHODS

Forty-four paired donor corneas were preserved after swab sample collection and povidone-iodine decontamination. Right and left corneas were immersed in Kerasave and Optisol-GS, respectively, and stored at 4°C before the initial evaluation. Paired corneas were assigned to processing subgroups for penetrating keratoplasty (n = 20), Descemet stripping automated endothelial keratoplasty (n = 14), or Descemet membrane endothelial keratoplasty (n = 10). Endothelial cell density, central corneal thickness, slit-lamp examination, and endothelial cell damage were assessed at different intervals. Sterility testing was performed on media samples.

RESULTS

At the initial evaluation, after 25.6 ± 3.2 hours of storage, the mean central corneal thickness of all corneas in Kerasave (n = 22) was greater than those in Optisol-GS (n = 22) (571 ± 12 μm vs. 526 ± 10 μm, respectively; P = 0.006). All other metrics were comparable between Kerasave and Optisol-GS in processing subgroups at all time intervals. Corneal swabs were positive in 90% of corneas before decontamination with povidone-iodine. At the initial evaluation, fungal contamination was detected in 24% and 19% of Kerasave and Optisol-GS, respectively. At the final evaluation, no fungi was detected in Kerasave and 1 Optisol-GS sample was positive (P = 0.999).

CONCLUSIONS

Metrics of corneas stored in Kerasave and Optisol-GS were comparable. Kerasave might be considered an antifungal-possessing alternative to Optisol-GS.

Fungal infection after keratoplasty and the role of antifungal supplementation to storage solution: a review

Fungal infection after corneal transplantation is a rare, yet potentially devastating, postoperative complication and has become a growing concern for the transplant surgeon and eye banking community. The Eye Bank Association of America (EBAA) has reported an increasing trend in the rate of postkeratoplasty fungal infections and a reversal in the previously documented predominance of bacterial over fungal infections. Additionally, several studies have confirmed a high correlation between positive corneoscleral donor rim fungal cultures and postoperative infections. Optisol GS (Bausch & Lomb, Irvine, California, USA), the most extensively used corneal storage solution in US eye banks, does not currently contain any antifungal supplementation. Although large randomised control trials evaluating the efficacy and safety of routine antifungal supplementation to corneal storage solution are lacking, several investigative studies have assessed the role of antifungal agents in reducing fungal contamination of donor corneas without causing undue corneal toxicity. This review will present the current epidemiology of postkeratoplasty fungal infections and evidence for obtaining routine fungal rim cultures and antifungal supplementation of storage solution.

Effect of Optisol Supplementation With 0.255 μg/mL Amphotericin B on Elimination of Yeast at 5°C

PURPOSE

Fungal infections in lamellar keratoplasty are a growing concern. Optisol-GS does not contain an antifungal agent and supplementation with 0.255 μg/mL Amphotericin B (AmpB) has been considered. This study tested the ability of 0.255 μg/mL AmpB in Optisol-GS to eliminate yeast contamination of corneal tissue.

METHODS

Three isolates of Candida albicans, 1 of Candida parapsilosis, and 1 of Candida glabrata were tested in Optisol with and without AmpB. Corneoscleral rims stored at -80°C were thawed and placed in 10 multiwell plates (4 per plate). The rims were inoculated with 4 respective loads of yeast: 0, 10, 10, and 10 colony-forming units in 2 sets of 5 for 5 yeasts. One set was filled with Optisol plus AmpB and the other with Optisol only. All 10 plates were incubated at cold storage (2°C-8°C) for 48 hours. After 48 hours, all corneal rims were placed into 10 mL of yeast extract peptone dextrose medium; a swab culture of each well was plated onto Sabouraud plates; and all plates with the remaining Optisol were incubated at 30°C. Yeast growth was monitored for 10 days. Minimum inhibitory concentration and minimum fungicidal concentration were determined.

RESULTS

All corneoscleral specimens were positive regardless of fungal load or presence of AmpB. All controls remained negative. Minimum inhibitory concentrations and minimum fungicidal concentrations were equivalent and ranged between 0.5 and 2.0 μg/mL.

CONCLUSIONS

AmpB at a concentration of 0.255 μg/mL in Optisol-GS at cold storage (2°C-8°C) over 48 hours did not eliminate yeast from corneal tissue.

Microbiological Screening of Hypothermic Preserved Donor Corneas in Keratoplasty

Purpose: To determine the prevalence, risk factors and microbial profiles of donor corneal contamination and its association with postoperative infection. Materials and Methods: 1348 hypothermic preserved donor corneas were screened during keratoplasty to assess the impacts of donor age, gender, cause of death and corneal preservation time on the contamination risk. The microbial spectrum and antibiotic sensitivity of causative microorganisms and the prognostic role of corneoscleral rim cultures were analyzed. Results: 111 donor corneas (8.2%) had positive microbial cultures, with 84 contaminated by bacteria, 25 by fungi and 2 by both. Acinetobacter baumannii complex (19.8%) and Candida spp. (9.0%) were the most commonly isolated bacteria and fungi, respectively. Two patients (1.8%) who received contaminated corneal buttons developed postoperative infections. Death due to cardiac disease led to more corneal contaminations than death due to brain disease (odds ratio (OR) = 2.59, P = .009). Longer preservation time was associated with a trend toward increasing contamination rate (from 8.3% to 15.0%). Moreover, fungal-contaminated corneas were preserved longer than bacterial-contaminated corneas (6.6 ± 4.5 versus 10.2 ± 5.4 days, P = .001). Corneas from donors who died from cardiac diseases and trauma showed the highest prevalence of bacterial (10.9%) and fungal (2.6%) contamination, respectively. Antibiotic sensitivity testing revealed that the third-generation fluoroquinolone levofloxacin had high rates of susceptibility to both gram-positive (G+) (60.0%) and gram-negative (G-) (44.6%) bacteria. Conclusions: The causes of donor corneal contamination are multifactorial. The antibiotic resistance rate of contaminating microbes seems to be increasing. Whether antibiotic usage in storage medium and postoperative prophylaxis should be updated accordingly warrants further investigation.

Reports of Post-keratoplasty Infections for Eye Bank-prepared and Non-Eye Bank-prepared Corneas: 12 Years of Data From a Single Eye Bank

PURPOSE

To examine postoperative reports of infection rates for eye bank-prepared and non-eye bank-prepared corneas from January 1, 2006 to December 31, 2017, from a single eye bank.

METHOD

A retrospective review of reported fungal and bacterial infections with corneal transplant surgeries using corneas distributed by our eye bank was conducted. The reported number of infections for corneas that underwent eye bank preparation (pre-cut and pre-stripped corneas) and for those distributed without eye bank preparation was quantified. The potential association between infection rates in tissue prepared by the eye bank and those in corneas that had no additional eye bank processing was also examined.

RESULTS

Four of 17,035 corneas distributed during the study period were associated with fungal infections (1 eye bank-prepared and 3 non-eye bank-prepared corneas) and were attributed to the tissue after investigation by eye bank medical directors. There was no ascending trend of infections reported with eye bank-prepared corneas in the first 3 years (2 of 1054 corneas, 0.19%) compared with that in the last 3 years of the study period (6 of 3500 corneas, 0.17%; P = 0.901) when the eye bank distributed 3 times more prepared corneas than non-eye bank-prepared corneas. A significant increase in the numbers of reported infections for non-eye bank-prepared corneas was observed between these 3-year intervals (0.1% in the first 3 years to 1.58% in the last 3 years; P = 0.001).

CONCLUSIONS

Reports of infections remained low despite increased use of eye bank-prepared tissue. These results suggest that factors other than eye bank tissue preparation should be considered when investigating potential sources of pathogen contamination in donor corneas.

Monitoring the microbial contamination of donor cornea during all preservation phases: A prospective study in the Eye Bank of Rome

BACKGROUND

In most European eye banks, human donor corneas are microbiologically tested after storage in organ culture conditions, and the tissues that are free of contamination are distributed for transplantation. In this prospective study, 100 donor corneas were tested for microbial contamination after cold storage, corneal culture and corneal deswelling at the Eye Bank of Rome.

METHODS

Samples of cold storage medium (EUSOL-C), corneal culture medium (TISSUE-C) and deswelling medium (CARRY-C) were tested after three, seven and one days of corneal storage, respectively. The CARRY-C medium, used to transport the cornea to the operation theatre, was retested 1 day after transplantation. The TISSUE-C and CARRY-C media were also tested after removing antimicrobial and antifungal agents using a dedicated device.

RESULTS

We found 67% of the EUSOL-C samples were contaminated mainly by Staphylococcus spp, 14% of TISSUE-C media were contaminated by bacteria and fungi and 3% of CARRY-C media by Staphylococcus spp The analysis performed after removing the antimicrobial and antifungal agents showed growth in three additional TISSUE-C samples (S viridans, S haemolyticus and E faecalis) and one CARRY-C (S cerevisiae and P acnes).

CONCLUSION

Tissue contamination was unexpectedly high on arrival to the eye bank, indicating the need to review and update decontamination procedures during tissue recovery, and renew training for the recovery teams. Storing donor corneas in organ culture conditions significantly reduced the microorganism burden. Using devices to remove antimicrobial and antifungal agents from samples before testing can increase the sensitivity of the standard microbiological method, and thus help further reduce the risk of microbial transmission.

Fungal infection after endothelial keratoplasty: association with hypothermic corneal storage

PURPOSE

To compare the incidence of fungal infection after endothelial keratoplasty (EK) when donor tissue had been stored in hypothermic medium or organ culture.

METHODS

We describe the clinical features of 10 cases of fungal infection (keratitis or endophthalmitis) following EK identified at three European centres. Case definition was the culture of fungus or a positive PCR from the host cornea or anterior chamber after EK. A survey of the incidence of infection after EK was conducted by the European Eye Bank Association. The main outcome measure was the number of cases in which donor tissue had been stored in hypothermic medium compared with organ culture.

RESULTS

The 10 cases occurred between 2014 and 2017. All donor corneas had been stored in hypothermic medium sourced from three US eye banks. Three pairs of mate corneas caused infections in six recipients. Candida spp were identified from nine cases, with one isolate of Purpureocillium lilacinum. Data on 16 862 corneas supplied for EK were available from 16 European eye banks for the 5-year period from 2012. There were 17 reported cases of infection, of which 15 (88%) were fungal infections and 14 (82%) were Candida spp. Fungal infection was reported from 3 of 14 476 (0.02%) corneas supplied in organ culture compared with 12 of 2386 (0.50%) corneas supplied in hypothermic medium (p<0.0001). The incidence of infection after hypothermic storage was similar for material sourced from Europe (0.52%) or the USA (0.61%).

CONCLUSIONS

Infection after EK is strongly associated with Candida spp. The possible explanations for the higher incidence of infection when tissue is stored in hypothermic medium are discussed.

Incidence and Outcomes of Positive Donor Rim Cultures and Infections in the Cornea Preservation Time Study

PURPOSE

To assess donor rim culture results and outcomes of ocular infections in the Cornea Preservation Time Study (CPTS).

METHODS

Donor corneal rim cultures were optional. Donor characteristics were assessed for association with positive cultures using the Fisher exact test and Poisson regression analyses. Incidence rates of ocular infections were estimated, and 95% confidence intervals were calculated.

RESULTS

Cultures were performed in 784 (58.9%) of the 1330 cases. For the 0 to 7-day versus 8 to 14-day preservation time groups, respectively, positive fungal growth occurred in 10 of 397 (2.5%) versus 5 of 387 (1.3%) corneas (P = 0.30), whereas positive bacterial cultures occurred in 6 of 397 (1.5%) versus 4 of 387 (1.0%) corneas (P = 0.75). Surgeon-prepared tissue remained a significant risk for positive fungal cultures [relative risk (RR) of surgeon- versus eye-bank-prepared, 2.85; 95% CI (1.02-7.98)], whereas younger donors [RR per year of age, 0.96; 95% CI (0.93-1.00)] and accidental death donors [RR of accident versus disease, 3.71; 95% CI (1.36-10.13)] were at a greater risk for positive bacterial cultures. Fungal infection (Candida glabrata) developed in 1 (6.7%) of 15 recipients with a positive fungal culture, and no recipient infections occurred with positive bacterial culture. With one additional fungal keratitis (Candida albicans) and one bacterial endophthalmitis (E. coli) with no rim culture performed, a total of 2 of 1330 eyes (0.15%) developed fungal and 1/1330 eyes (0.08%) developed bacterial postkeratoplasty infections.

CONCLUSIONS

A longer preservation time was not associated with a higher rate of positive donor rim cultures. The overall rate of infection across the entire cohort was low.

Association between positive corneal rim cultures and microbiology screening protocols in Ontario

OBJECTIVE

(i) To assess the rate of positive microbiological cultures of corneas prepared by the Eye Bank of Canada (Ontario Division) between January 1, 2012, and December 31, 2013; (ii) to review the microbiology protocols at the 5 major transplant centres in Ontario; and (iii) to assess the incidence of endophthalmitis during the study period.

DESIGN

Retrospective chart review.

PARTICIPANTS

A total of 4186 consecutive cultured corneal tissues prepared by the Eye Bank from January 1, 2012, to December 31, 2013.

METHODS

Rates of culture-positive cornea rims and incidence of postkeratoplasty endophthalmitis at 5 surgical centres in Ontario were determined, and the protocols used to culture rims at each site were concurrently reviewed. Culture results were analyzed via logistic regression for positive cultures.

RESULTS

The rate of positive cultures at each sites were as follows: centre A, 3.74%; centre B, 3.26%; centre C, 0.51%; centre D, 0.48%; and centre E, 0.04%. Centres A, B, and D were noted to have significantly higher positive rates than centre E. In comparing microbiology protocols, longer incubation period (11 days) was 12 times more likely to be associated with higher positive culture rates than shorter period (4-5 days). Six-month follow-up of all keratoplasties revealed zero reported cases of endophthalmitis.

CONCLUSIONS

A literature review regarding the predictive value of routine culturing reveals conflicting data. Our findings suggest that differences in the microbiology protocols directly influence the rates of positive rim cultures. Without a standardized protocol, it is not possible to evaluate the predictive value of routine corneal rim culturing in predicting postkeratoplasty endophthalmitis.

Clinical features, antimicrobial susceptibilities, and treatment outcomes of patients with culture positive endophthalmitis after penetrating keratoplasty

Purpose

To report the clinical features organisms and treatment outcomes in patients with endophthalmitis after penetrating keratoplasty (PK)

Methods

Retrospective noncomparative case series.

Results

Eleven eyes of 11 patients with culture positive endophthalmitis after PK were included. The time to diagnosis of endophthalmitis from last PK was less than 1 week in 3/11 (27%), between 1 and 4 weeks in 3/11 (27%), and greater than one month in 5/11 (46%) (range 2–924 days). The distribution of isolates included gram positive (GP) 9/11 (82%), gram negative (GN) 1/11 (9%), and fungal 1/11 (9%) species, respectively. Of GP bacteria tested, 9/9 (100%) were sensitive to Vancomycin. Of fungal isolates tested, none (0/1) were sensitive to Amphoteracin, Fluconazole, and/or Voriconazole. Among patients with rim culture data available, 1/7 (14%) donor rims were culture positive for Candida glabrata and 6/7 (86%) were culture negative. Patients were treated with primary tap and inject in 10/11 (91%) and primary vitrectomy in 1/11 (9%). VA of ≥5/200 was present in 2/11 (18%) at time of endophthalmitis diagnosis, and was recorded in 6/11 (55%) at last follow-up.

Conclusions and Importance

Patients with endophthalmitis after PK presented at variable time points after surgery. Gram positive organisms were the most common isolate. VA outcomes after treatment were generally poor.

Association Between Fungal Contamination and Eye Bank-Prepared Endothelial Keratoplasty Tissue: Temperature-Dependent Risk Factors and Antifungal Supplementation of Optisol-Gentamicin and Streptomycin

Importance

Fungal contamination and infection from donor tissues processed for endothelial keratoplasty is a growing concern, prompting analysis of donor tissues after processing.

Objective

To determine whether eyebank-processed endothelial keratoplasty tissue is at higher risk of contamination than unprocessed tissue and to model eyebank processing with regard to room temperature exposure on Candida growth in optisol-gentamicin and streptomycin (GS) with and without antifungal supplementation.

Design, Setting, and Participants

An examination of the 2013 Eversight Eyebank Study follow-up database for risk factors associated with post-keratoplasty infection identified an increased risk of positive fungal rim culture results in tissue processed for endothelial keratoplasty vs unprocessed tissue. Processing steps at room temperature were hypothesized as a potential risk factor for promotion of fungal growth between these 2 processes. Candida albicans, Candida glabrata, and Candida parapsilosis endophthalmitis isolates were each inoculated into optisol-GS and subjected to 2 different room temperature incubation regimens reflective of current corneal tissue handling protocols.

Main Outcomes and Measures

Eversight Eyebank Study outcomes and measures were follow-up inquiries from 6592 corneal transplants. Efficacy study outcomes and measures were fungal colony-forming units from inoculated vials of optisol-GS taken at 2 different processing temperatures.

Results

Donor rim culture results were 3 times more likely to be positive for fungi in endothelial keratoplasty-processed eyes (1.14%) than for other uses (0.37%) (difference, 0.77%; 95% CI, 0.17-.1.37) (P = .009). In vitro, increased room temperature incubation of optisol-GS increased growth of Candida species over time. The addition of caspofungin and voriconazole decreased growth of Candida in a species-dependent manner.

Conclusions and Relevance

Detectable Candida growth in donor rim cultures, associated with a higher rate of post keratoplasty infection, is seen in endothelial keratoplasty tissue vs other uses at the time of transplantation, likely owing in part to eyebank preparation processes extending the time of tissue warming. Reduced room temperature incubation and the addition of antifungal agents decreased growth of Candida species in optisol-GS and should be further explored to reduce the risk of infection.

Rapid Warming of Donor Corneas Is Safe and Improves Specular Image Quality

PURPOSE

To determine whether warming donor corneas to near-physiological temperatures can safely shorten warming times while providing high-quality specular images during tissue evaluation.

METHODS

Mated corneas were warmed at room temperature (RT) or at 35°C for 4 hours upon removal from cold storage. Specular images and endothelial cell densities were acquired and rated every hour. Additional mated corneas were subjected to 2 rounds of 4-hour incubation at either RT or 35°C. Endothelial cell loss (ECL) was quantified 14 days after the initial incubation using Calcein-acetoxymethyl (Calcein-AM) and FIJI trainable segmentation. Cultures inoculated with common ocular pathogens were subjected to 2 warming cycles at RT for 4 hours or 35°C for 2 hours. Colony counts were taken over the course of 2 weeks after inoculation.

RESULTS

Specular image quality ratings were consistently higher for corneas warmed at 35°C compared with those at RT. Image quality ratings for corneas warmed at 35°C for 1.5 hours were higher than corneas warmed at RT for 4 hours (P = 0.04). No differences in ECL were observed between the 2 warming conditions (RT = 13.1% ± 7.6% ECL, 35°C = 13.9% ± 6% ECL, P = 0.75). There was no difference in colony counts for pathogens tested between the 2 warming conditions.

CONCLUSIONS

Warming donor corneas to near-physiological temperatures for a short time can increase specular image quality while reducing the time tissues are unrefrigerated at eye banks. This method allows for more efficient specular imaging without inducing additional ECL or increasing pathogen growth.

Systemic Fungal Infections in Donors for Corneal Transplantation

PURPOSE

To determine the prevalence of postkeratoplasty fungal infection when corneal tissue from donors with a recent medical history of oral thrush or respiratory, urine, wound, sputum, bronchial, tracheal, or throat culture positive for fungus is identified before recovery and after decontamination of the corneal tissue with 5% povidone-iodine flush to the donors' eyes during recovery.

METHODS

This is a prospective analysis of corneas from 42 donors with a documented medical history of fungus or positive fungal culture, which were recovered between January 2010 and November 2010. Standard aseptic swab of the donors' corneas before and after application of 5% povidone-iodine solution was performed. Culture results were analyzed in relationship to the donors' medical history and potential posttransplantation infections.

RESULTS

Eighty-four eyes from 42 patients were swabbed for cultures during the study period. Seven eyes (8.3%) were positive for fungal growth before treatment with 5% povidone-iodine, whereas there were no positive fungal cultures after treatment (P = 0.007). Fifty-four corneas from this study group were used for corneal transplantation. There were no cases of fungal infection in any postkeratoplasty eyes transplanted from this study group.

CONCLUSIONS

In this small study, the overall prevalence of fungal infections after corneal transplantation using corneal donor tissue from donors with a fungal-positive medical history is low. Corneal fungal contamination in donors with a history of fungal infection or a positive fungal culture can be significantly reduced with a 5% povidone-iodine flush.

Incidence and Outcomes of Positive Donor Corneoscleral Rim Fungal Cultures after Keratoplasty

PURPOSE

To determine the incidence of positive corneoscleral donor rim fungal cultures after keratoplasty and to report clinical outcomes of grafts with culture-positive donor rims.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Consecutive donor corneas and keratoplasty recipients at a single tertiary referral center over 20 years.

METHODS

Patient charts were reviewed to determine the incidence of positive donor rim fungal cultures and clinical outcomes of all grafts using contaminated tissue.

MAIN OUTCOME MEASURES

The primary outcome measures were positive donor rim fungal culture results and the development of postkeratoplasty fungal infection using corresponding corneal tissue. The secondary outcome measure was the impact of postoperative prophylaxis on donor tissue-associated infections.

RESULTS

A total of 3414 keratoplasty cases were included in the statistical analysis. Seventy-one cases (2.1%) were associated with a fungal culture-positive donor rim. Candida species were cultured in 40 cases (56.3%). There was a higher incidence of positive rim cultures over the last 5 years of the analytic period compared with the first 15 years (P = 0.018). Fungal keratitis developed in 4 cases (5.6%), and all patients required further surgical intervention to achieve cure. There were no cases of fungal endophthalmitis. Empiric antimycotic prophylaxis initiated at the time of positive culture result reduced the incidence of keratitis from 15.8% in untreated cases to 1.9% in treated cases (P = 0.056).

CONCLUSIONS

Positive donor rim fungal cultures are uncommon, but carry an unacceptably high risk of postoperative fungal infection. This risk may be reduced with prophylactic antimycotic therapy when culture-positive donor rims are identified.

Conjunctival and intraocular swabs for the microbiological assessment of donor corneas

PURPOSE

In this study, we investigated the associations between conjunctival (co) and intraocular (io) swabs and their implications for the contamination rates of organ-cultured corneas.

METHODS

A total of 4177 swabs from 1054 corneas of 527 donors were acquired from the conjunctiva, after disinfection with 5% polyvinylpyrrolidone-iodine solution, and also from the anterior chamber after corneoscleral trepanation (io). Samples were incubated at 22.5 ± 2.5°C and 32.5 ± 2.5°C in thioglycollate broth for 14 days. Donor corneas were cultured in a closed system at 31°C. Microbial differentiation was performed for positive cultures.

RESULTS

A higher temperature (32.5°C) and the intraocular swab retrieving localization led to significantly higher swab positive rates (32.5°C versus 22.5°C, odds 1.65, p < 0.0001; io versus co, odds 1,53, p < 0.0001). Death-to-collection time and laterality (left or right eye) had no significant influence on swab positivity. The cause of death significantly influenced the positive rates (p < 0.0001). Detection at 32.5°C occurred significantly earlier than at 22.5°C (p < 0.0001). The overall comparison of detected species showed no significant differences in the variety between intraocular and conjunctival swabs. During the study period, six contaminations of organ-cultured corneas occurred: four times Pseudomonas aeruginosa and once each Candida albicans and Staphylococcus hominis were found. Swap results and cornea contaminations were not significantly correlated.

CONCLUSIONS

Co and io swabs show high microbial colonization rates, even after standard disinfection. Io swabs generally reproduce the co microbial range, most likely due to a mobilization and diversion of microorganisms during the trepanation procedure. Swab results do not yield a valuable tool to predict contaminations of organ-cultured corneas.

Current Concepts in the Management of Unique Post-keratoplasty Infections

As corneal transplantation has evolved, the spectrum of post-surgical infection has changed and often presents a diagnostic and therapeutic challenge. Lamellar techniques hold the potential of improved outcomes and decreased post-operative complications, however, they create a lamellar interface, which is a potential space for sequestration of infectious organisms. In addition, while keratoprosthesis offers vision to patients who are poor candidates for traditional keratoplasty, infectious complications can be severe and sight threatening. Although antimicrobials remain the mainstay of treatment, definitive management often requires surgical intervention.

Eye banking and corneal transplantation communicable adverse incidents: current status and project NOTIFY

PURPOSE

Evidence of the transmission of disease via donor ocular tissue has been demonstrated for adenocarcinoma, rabies, hepatitis B virus, cytomegalovirus, herpes simplex virus, Creutzfeldt-Jakob disease, and a variety of bacterial and fungal infections.

METHODS

Although there is no evidence to date of disease transmission for HIV infection, syphilis, hepatitis C, hepatitis A, tuberculosis, HTLV-1 and -2 infection, active leprosy, active typhoid, smallpox, and active malaria, these entities remain contraindications for transplantation for all eye banks nationally and internationally. The potential sources of contamination include infected donors, during the process of removing tissue from cadaveric donors, the processing environment, and contaminated supplies and reagents used during processing. The transmissions of Herpes simplex virus and HSV via corneal graft have been shown to be responsible for primary graft failure. HSV-1 may also be an important cause of PFG.

RESULTS

The long latency period of some diseases, the emergence of new infectious disease, and the reemergence of others emphasize the need for long-term record maintenance and effective tracing capabilities.

CONCLUSIONS

The standardization of definitions for adverse events and reactions will be necessary to support the prevention and transmission of disease. International classification of a unique identification system for donors will be increasingly important for vigilance and traceability in cross-national exportation of human cells, tissues, and cellular- and tissue-based products. Opportunities for continuous improvement exist as does the need for constant vigilance and surveillance.

Endophthalmitis following keratoplasty: incidence, microbial profile, visual and structural outcomes

PURPOSE

To identify the causative organisms of post-keratoplasty endophthalmitis and to report its visual and structural outcomes.

METHODS

A chart review was performed of all patients diagnosed with endophthalmitis after keratoplasty at a tertiary hospital between January 1990 and January 2007.

RESULTS

Endophthalmitis developed in 55 cases in the penetrating keratoplasty group and in no cases in the lamellar keratoplasty group. The majority of isolated microbes were gram-positive (86.3%). Only 1 eye retained a clear graft with 20/25 vision; other cases had ≤20/200 vision. Four of 13 eyes that underwent vitrectomy and 28 of 42 that did not undergo vitrectomy ended up with no light perception. One eye that underwent vitrectomy and 21 eyes that did not undergo vitrectomy were eviscerated.

CONCLUSIONS

Post-keratoplasty endophthalmitis was associated with poor visual and structural outcome. Gram-positive organisms were the most common cause of infection. Early vitrectomy may reduce functional and structural damage associated with endophthalmitis.

Report of the Eye Bank Association of America medical advisory board subcommittee on fungal infection after corneal transplantation

PURPOSE

To investigate the incidence of fungal infections after corneal transplantation to determine whether storage media supplementation with an antifungal should be considered.

METHODS

Adverse reactions reported to the Eye Bank Association of America through the online adverse reaction reporting system between January 1, 2007, and December 31, 2010, were reviewed to identify cases of recipient fungal infection. Data were collected regarding the donor, the donor cornea, recovery and processing, and mate culture and clinical course of the recipients.

RESULTS

Thirty-one cases of culture-proven fungal keratitis (n = 14) and endophthalmitis (n = 17) were reported out of 221,664 corneal transplants performed using corneal tissue distributed by domestic eye banks (1.4 cases per 10,000 transplants performed). Although the annual incidence of postkeratoplasty fungal infection has not increased significantly since 2005, a trend toward an increasing rate of fungal infection has been observed. Fungal infections were more commonly reported after endothelial keratoplasty procedures (0.022%) than penetrating keratoplasty procedures (0.012%), but the difference was not statistically significant (P = 0.076). Additionally, no association was found between fungal infection after endothelial keratoplasty and whether the lamellar tissue cut was performed by the surgeon or the eye bank technician. Seventy-three percent (16 of 22) of the fungal cultures performed on the mate corneas were positive, with infection developing in 67% (10 of 15) of recipient eyes (endophthalmitis in 6 eyes and keratitis in 4 eyes).

CONCLUSIONS

Although a nonsignificant increasing trend in the rate of fungal infection has been observed over the past 6 years, it is not sufficiently compelling to pursue antifungal supplementation of donor storage media.

Endophthalmitis: A review of recent trends

Endophthalmitis is a feared complication of trauma, surgical procedures and septicemia. Although uncommon, its potential for significant visual loss is well recognized. Especially over the past decade, complicated surgeries and medical techniques have increased and seriously ill patients are being sustained in ever increasing numbers. New pathogens are being recognized and known ones reclassified thanks to advances in molecular analysis. Continuously evolving PCR methodologies also add a new dimension to the diagnosis of infectious endophthalmitis. As well, medical literature is now truly international, encompassing studies from around the world that expand our understanding of ocular infectious disease. This report reviews some of these changes as they relate to endophthalmitis and particularly to the spectrum of organisms involved.

The safety and efficacy of linezolid and daptomycin as an additive in Optisol-GS against methicillin-resistant Staphylococcus aureus

PURPOSE

To evaluate the efficacy of adding either linezolid or daptomycin to Optisol-GS donor storage medium in reducing methicillin-resistant Staphylococcus aureus (MRSA) contamination of donor corneas.

METHODS

Optisol-GS was supplemented with either linezolid at 2×, 4×, or 10× minimum inhibitory concentration (MIC) or daptomycin and calcium at 5× or 50× MIC. Unsupplemented control groups were also used. Gentamicin-sensitive and gentamicin-resistant isolates of MRSA were added, and vials were refrigerated for 48 hours followed by sampling for viable colony counts immediately upon removal from refrigeration and after warming to room temperature for 3 hours. Safety studies of Optisol-GS supplemented with 50× MIC daptomycin and calcium were performed by evaluating the central corneal thickness and endothelial cell density of the donor cornea. Stability of daptomycin in Optisol-GS at storage was also tested.

RESULTS

No added benefit was observed with linezolid supplementation to Optisol-GS against gentamicin-sensitive MRSA, with reduction in viable colony counts by >90% in all groups. No benefit was observed with linezolid supplementation against gentamicin-resistant MRSA, with the majority of inocula remaining viable in all groups. Viable counts of gentamicin-sensitive MRSA and gentamicin-resistant MRSA were effectively reduced with both 5× MIC and 50× MIC daptomycin supplementation. 50× MIC daptomycin-supplemented Optisol-GS had no appreciable effect on the central corneal thickness or endothelial cell density of the donor cornea and was stable at storage for 14 days.

CONCLUSIONS

The addition of daptomycin to Optisol-GS significantly increases the anti-MRSA activity of the medium without any apparent negative effects on donor corneal tissue.

Conjunctival swabs and corneoscleral rim cultures from corneal transplantation donors as possible early indicators for posttransplant endopthalmitis

PURPOSE

To determine by microbiological examinations the rate of conjunctiva and corneoscleral rim contamination of cadaver donor tissues.

METHODS

A prospective review of culture results for 98 cadaver donor conjunctival swabs [mean age 76.4 ± 12.9 years (±SD)]. Transplant patients were evaluated both before and after disinfection with gentamicin. Individual parameters evaluated included detection rates of bacteria, variety of detected bacteria, time interval from donor death to tissue harvest and age of donors.

RESULTS

Before disinfection, 60 out of 98 conjunctival swabs exhibited microbial growth, while only 36 out of 98 exhibited growth after disinfection (p = 0.0006). Longer intervals between death and tissue harvest were associated with higher positive microbial growth rates. Prior to disinfection, culture-positive donors (74.1 ± 13.6 years) were significantly younger than culture-negative donors (79.8 ± 10.8 years) (p = 0.024). Positive donor rim cultures were noted in 2 out of the 22 corneal transplantations. Microorganisms isolated from the corneal grafts matched those found in the conjunctiva.

CONCLUSIONS

It is recommended that the corneoscleral buttons be removed as soon as possible. Cultures of conjunctival swabs collected from donors after disinfection may be useful in determining treatment for postoperative infections occurring after corneal transplantation.

Comparison of the pig and feline models for full thickness corneal transplantation

PURPOSE

The goal of this study was to report on the advantages and limitations of the pig and feline models for experimental in vivo corneal transplantation.

METHODS

Ten healthy domestic pigs and ten healthy cats were used. Full thickness penetrating keratoplasty was performed using autologous (eight cases), allogeneic (seven cases) or human xenogeneic (three cases) tissue. In two other cases, the inflammatory response to partial thickness trephination (without transplantation) was evaluated. Eyes were assessed daily before and after surgery by slit-lamp, pachymetry, and tonometry. A transparency score ranging from 0 (opaque graft) to 4 (clear graft) was used, based on the slit-lamp examination. Optical coherence tomography, histology, and electron microscopy were performed postmortem.

RESULTS

In the pig, the mean (±SD) transparency score for the eight full thickness grafts was 0.88 ± 0.99, ranging from 0 to 3. In the feline model, the mean transparency score for the seven uncomplicated grafts was 3.93 ± 0.19, ranging from 3.5 to 4. Both negative controls without endothelium remained opaque at all time. Intraoperative tendency for iris incarceration into the wound, rapid corneal swelling, suture cheese wiring, and postoperative intraocular inflammation were the main factors jeopardizing the functional success of the corneal transplant in the pig model.

CONCLUSION

Suboptimal functional results were obtained after full thickness corneal transplantation in the pig model, while in the feline model, the same protocol yielded uneventful surgeries and clear transplants, with functional results similar to those achieved in human subjects.