Microbial keratitis after penetrating keratoplasty

Non-Descemet stripping endothelial keratoplasty for bullous keratopathy in patients with atopic dermatitis: A long-term case report

RATIONALE

Patients with atopic dermatitis undergoing penetrating keratoplasty (PKP) face a high risk of postoperative complications. Endothelial keratoplasty may be a safer alternative for such patients, including those with abnormal anterior chamber anatomy.

PATIENT CONCERNS

3 male patients, aged 33 to 44, presented with blurred vision at Keio University Hospital.

DIAGNOSIS

Bullous keratopathy was diagnosed through slit-lamp examination and specular microscopy. Two patients had well-controlled systemic atopic dermatitis, while 1 had blepharitis associated with atopic dermatitis. Two patients had peripheral anterior synechia, and 2 had undergone glaucoma surgery before keratoplasty.

INTERVENTIONS

Non-Descemet stripping endothelial keratoplasty (nDSAEK) was performed by a single surgeon.

OUTCOMES

The best-corrected visual acuity ranged from 0.7 to 1.5 logMAR before surgery and from 0.2 to 2.3 logMAR after surgery. One year post-surgery, the graft remained clear in 2 cases; however, in the case of repeated glaucoma surgeries after nDSAEK, the graft became edematous. Corneal endothelial cell density was 1586 and 1988 cells/mm² in 2 cases and undetectable in the failed case. The follow-up period ranged from 2.5 to 9 years.

LESSONS

Despite the presence of peripheral anterior synechia or prior glaucoma surgery, some patients experienced a favorable long-term postoperative course following nDSAEK. This procedure may offer a safer alternative for treating patients with atopic dermatitis who have ocular complications that present a high risk for PKP.

Post-Keratoplasty Microbial Keratitis in the Era of Lamellar Transplants-A Comprehensive Review

Microbial keratitis in a post-transplant cornea should be considered a distinct entity from microbial keratitis in a non-transplant cornea. Firstly, the use of immunosuppressive treatments and sutures in corneal transplants changes the etiology of keratitis. Secondly, corneal transplant has an impact on corneal biomechanics and structure, which facilitates the spread of infection. Finally, the emergence of lamellar transplants has introduced a new form of keratitis known as interface keratitis. Given these factors, there is a clear need to update our understanding of and management strategies for microbial keratitis following corneal transplantation, especially in the era of lamellar transplants. To address this, a comprehensive review is provided, covering the incidence, risk factors, causes, and timing of microbial keratitis, as well as both clinical and surgical management approaches for its treatment in cases of penetrating and lamellar corneal transplants.

Infectious keratitis following corneal transplantation: A long-term cohort study

BACKGROUND

To assess the long-term incidence and risk factors for post-keratoplasty infectious keratitis (IK), associated ocular pathogens, and antibiotic resistance profiles.

METHODS

Cohort study including 2553 consecutive penetrating, endothelial, and anterior lamellar keratoplasties performed between 1992 and 2020. Medical and microbiological records of patients clinically diagnosed with IK were retrospectively reviewed.

MAIN OUTCOME MEASURES

cumulative incidence of IK, infectious agent species, and antibiotics resistance profiles.

RESULTS

The average follow-up time after transplantation was 112 ± 96 months. Eighty-nine IK episodes were recorded; microbiological tests were positive in 55/89 (62%). The cumulated incidence of postoperative IK was 5.50%/10.25% at 10/20 years. The occurrence of at least one episode of IK after transplantation was associated with lower graft survival in the long term (p < 0.0001). Rejection risk (adjusted Hazard Ratio, 2.29) and postoperative epithelial complications (HR, 3.44) were significantly and independently associated with a higher incidence of postoperative IK. Infectious agents included 41 bacteria, 10 HSV, 6 fungi, and 1 Acanthamoeba. The rate of antibiotic resistance was 0% for vancomycin, 13% for fluoroquinolones, 20% for rifamycin, 59% for aminoglycosides, and 73% for ticarcillin. In 41% of cases, patients were under prophylactic topical antibiotics before the infectious episode. Topical antibiotics were significantly associated with increased resistance to penicillin, carbapenems, and aminoglycosides.

CONCLUSION

IK (mainly bacterial) is a frequent complication of corneal transplantation in the long term. Vancomycin and fluoroquinolones can be considered as first-line treatments. Prolonged postoperative antibiotic preventive treatment is not advisable as it may increase antibiotic resistance.

Atypical microbial keratitis

Atypical microbial keratitis refers to corneal infections caused by micro-organisms not commonly encountered in clinical practice. Unlike infections caused by common bacteria, cases of atypical microbial keratitis are often associated with worse clinical outcomes and visual prognosis. This is due to the challenges in the identification of causative organisms with standard diagnostic techniques, resulting in delays in the initiation of appropriate therapies. Furthermore, due to the comparatively lower incidence of atypical microbial keratitis, there is limited literature on effective management strategies for some of these difficult to manage corneal infections. This review highlights the current management and available evidence of atypical microbial keratitis, focusing on atypical mycobacteria keratitis, nocardia keratitis, achromobacter keratitis, and pythium keratitis. It will also describe the management of two uncommonly encountered conditions, infectious crystalline keratopathy and post-refractive infectious keratitis. This review can be used as a guide for clinicians managing patients with such challenging corneal infections.

Current Perspectives on Corneal Transplantation

Disease of the cornea is the third leading cause of blindness worldwide. Corneal graft surgery is one of the most successful forms of solid organ transplantations in humans, with ever-increasing developments in surgical technique. To date, approximately 4504 corneal transplants are performed in the United Kingdom each year. While full thickness transplantation was the most commonly performed keratoplasty over the last few decades, selective lamellar transplantation of the diseased layers of the cornea has been universally adopted. This comprehensive review aims to provide an updated synthesis on different types of corneal transplantations, their treatment outcomes, and the associated complications of each procedure in both adult and paediatric population. In addition, we also present an up-to-date summary of the emerging therapeutic approaches that have the potential to reduce the demand for donor-dependent keratoplasty.

Combined Photoactivated Chromophore for Infectious Keratitis-Corneal Collagen Cross-Linking (PACK-CXL) and Therapeutic Penetrating Keratoplasty for Resistant Bacterial Keratitis

Purpose

Methods

Results

Conclusion

Post penetrating keratoplasty infectious keratitis: Clinico-microbiological profile and predictors of outcome

PURPOSE

To study the clinico-microbiological profile, outcomes and prognostic factors of post penetrating keratoplasty (PKP) infectious keratitis.

METHODS

Retrospective review of medical records of 78 patients with post PKP infectious keratitis presenting between January 2014 and December 2018. Demographic, clinical and microbiological profile was documented and predictors of treatment and graft success were evaluated using univariate and subsequent multivariate logistic regression analysis.

RESULTS

Mean age of patients was 52.17 ± 15.51 years and mean infiltrate size was 19.39 ± 19.68 mm². Mean duration of presentation with infection post PKP was 11.66 ± 10.65 months. Culture positivity was seen in 64 eyes (82.05%). Bacterial growth was observed in 47 eyes (60.25%), fungal growth in 17 (21.79%) and no microbiological growth in 14 eyes (17.94%). At 3 months the visual acuity (VA) improved in 37 eyes (47.44%), did not change in 27 (34.62%) and deteriorated in 14 (17.95%). Graft failure was noted in 53 eyes (73.08%). Surgical intervention was needed in 47 (60.25%) eyes of which most common was therapeutic PKP in 32 eyes (41.02%). Treatment failure was noted with fungal infection (p = 0.05), poorer vision at presentation (p = 0.02), larger infiltrate area (p = 0.002) and graft infection developing before 1 year (p = 0.02). Graft failure was noted with associated endophthalmitis (p = 0.02), poorer VA at presentation (p = 0.01) and larger infiltrate area (p = 0.02).

CONCLUSION

Post PKP infectious keratitis is a sight threatening ocular condition. It is associated with high incidence of graft failure and frequently requires surgical intervention. Fungal etiology, larger infiltrate size, poorer vision at presentation and associated endophthalmitis carries a poorer prognosis.

Prognostic Factors Affecting Graft Survival in Patients Undergoing Penetrating Keratoplasty for Infectious Keratitis

Objectives:

To evaluate the prognostic factors affecting graft survival in patients undergoing penetrating keratoplasty (PKP) for infectious keratitis.

Materials and Methods:

Patients who underwent PKP for keratitis in our hospital between 2013 and 2018 were retrospectively reviewed. Patients who underwent therapeutic PKP at the inflammatory stage and were followed for at least 12 months were included in the study. Age, gender, follow-up period, time between diagnosis and surgery, lens status, presence of limbal involvement, presence of corneal ulceration, perforation, or corneal abscess, type of microorganism detected in culture, number of fortified medications used before surgery and duration of use, preoperative and postoperative visual acuity, postoperative graft transparency, postoperative complications, recurrence of infection, rate of re-keratoplasty, and indication for and timing of re-keratoplasty were recorded. The relationship between these findings and anatomic, therapeutic, and functional success were evaluated.

Results:

Fifty-nine patients were included in the study; 40 (67.8%) were male and 19 (32.2%) were female, and the mean age was 59.78±19.46 (6-91) years. Anatomic success was achieved in 58 patients (98.3%). Therapeutic success was achieved in 47 patients (79.7%) and there was a significant relationship between therapeutic success and re-keratoplasty and early re-keratoplasty (p<0.001 for both). Thirty-two patients (54.2%) had functional success and there was a significant relationship between the absence of postoperative complications and functional success (p=0.014).

Conclusion:

PKP is an effective treatment option in treatment-resistant keratitis or keratitis with impending perforation. The absence of postoperative complications and performing early re-keratoplasty in patients with recurrence increase the success rate.

Post-keratoplasty Infectious Keratitis: Epidemiology, Risk Factors, Management, and Outcomes

Post-keratoplasty infectious keratitis (PKIK) represents a unique clinical entity that often poses significant diagnostic and therapeutic challenges. It carries a high risk of serious complications such as graft rejection and failure, and less commonly endophthalmitis. Topical corticosteroids are often required to reduce the risk of graft rejection but their use in PKIK may act as a double-edged sword, particularly in fungal infection. The increased uptake in lamellar keratoplasty in the recent years has also led to complications such as graft-host interface infectious keratitis (IIK), which is particularly difficult to manage. The reported incidence of PKIK differs considerably across different countries, with a higher incidence observed in developing countries (9.2-11.9%) than developed countries (0.02-7.9%). Common risk factors for PKIK include the use of topical corticosteroids, suture-related problems, ocular surface diseases and previous corneal infection. PKIK after penetrating keratoplasty or (deep) anterior lamellar keratoplasty is most commonly caused by ocular surface commensals, particularly Gramme-positive bacteria, whereas PKIK after endothelial keratoplasty is usually caused by Candida spp. Empirical broad-spectrum antimicrobial treatment is the mainstay of treatment for both PKIK, though surgical interventions are required in medically refractory cases (during the acute phase) and those affected by visually significant scarring (during the late phase). In this paper, we aim to provide a comprehensive overview on PKIK, encompassing the epidemiology, risk factors, causes, management and outcomes, and to propose a treatment algorithm for systematically managing this challenging condition.

Microbial keratitis and clinical outcomes following penetrating and endothelial keratoplasty

PURPOSE

The goal of this study was to review the incidence, risk factors and outcomes of microbial keratitis after penetrating keratoplasty (PK) and endothelial keratoplasty (EK).

METHODS

The electronic medical records at Wills Eye Hospital were queried for cases of microbial keratitis following PK or EK performed between 1 May 2007 and 1 September 2018. Charts were reviewed to obtain demographic data, transplant characteristics, details of microbial keratitis, graft survival and clinical outcomes.

RESULTS

During the study period, 2098 transplants were performed in 1601 patients. Of these, 1267 (60.4%) were PKs and 831 (39.6%) were EKs. We identified 86 (4.1%) cases of subsequent microbial keratitis. The incidence of microbial keratitis after PK was significantly higher than after EK (5.9% versus 1.3%; p = 0.005). Furthermore, the rate of infection was higher after repeat transplants (either PK or EK) compared to initial keratoplasties (5.5% versus 3.4%; p = 0.02). Twenty-six (32.1%) grafts remained clear at most recent follow-up after microbial keratitis, and the proportion of clear grafts was higher after EK than PK (66.7% versus 27.8%; p = 0.03).

CONCLUSION

Rates of microbial keratitis were significantly higher after PK compared to EK, and repeat transplantation was a risk factor for microbial keratitis. To the best of our knowledge, there is no prior study in the literature evaluating microbial keratitis rates after PK and EK and comparing outcomes.

Microbial Keratitis in Corneal Transplants: A 12-Year Analysis

Purpose

To investigate the frequencies, trends, and in vitro drug susceptibilities of the causative pathogens in corneal transplant microbial infections in Manchester Royal Eye Hospital.

Methods

Corneal scrape results recorded by the microbiology service between 2004 and 2015 were extracted from an established database. This microbiological data was matched with a separate database of all corneal transplant procedures performed in our centre over this time period. Patient records were examined to collect specific patient data and to confirm the diagnosis of microbial keratitis.

Results

A total of 1508 grafts had been performed at our centre in this period. 72 episodes of graft microbial keratitis were identified from 66 eyes that had undergone keratoplasty procedures. Mean age was 56, and 51% of subjects were male. Ninety-three percent of microbial keratitis episodes occurred in penetrating keratoplasty procedures and 6% in deep anterior lamellar keratoplasty procedures. No endothelial grafts presented with infections throughout this time period. Of the 79 organisms identified, 73% were gram positive, 23% gram negative and 4% fungi. With regard to gram-positive organisms, vancomycin and gentamicin showed 100% and 91% susceptibility, respectively. Ofloxacin had a resistance rate of 13.7%. In terms of gram-negative organisms, gentamicin and chloramphenicol showed 100% sensitivity, with cefuroxime showing 69%. Resistance rates were less than 15% in all tested gram-negative antimicrobials.

Conclusion

This paper describes the largest collection of corneal transplant infections identified within the UK. This finding may aid clinicians in predicting possible causative organisms for microbial keratitis and aid antibiotic choice.

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.

Keratitis Caused by Candida parapsilosis and Subsequent Corynebacterium macginleyi Infection: Case Report and Short Review

Keratitis due to Candida parapsilosis or Corynebacterium macginleyi is uncommon. We present a patient with several risk factors who suffered two subsequent corneal infections caused by these pathogens and healed with topical conservative therapy. The important factor was the early detection of infection. Fluconazole solution administered topically as eye drops combined with regular debridement proved in this case a successful alternative to systemic antifungal treatment. With a perceived recurrence of the keratitis, one must take into account the involvement of other pathogens present. The previous use of an antifungal solution other than a conventional eye drop could be an additional risk factor for a second bacterial infection, but the benefits should still rule in favor of such a treatment.

Donor characteristics and risk factors for methicillin-resistant Staphylococcus aureus contamination in storage medium for corneal transplantation: A 10-year retrospective study

PURPOSE

This study investigated the donor characteristics of methicillin-resistant Staphylococcus aureus (MRSA) contamination in storage medium before transfer of corneas to preservation medium for corneal transplantation, in order to identify donor characteristic risk factors for MRSA contamination.

METHODS

This retrospective, cross-sectional study was performed using Juntendo Eye Bank records for all corneal transplantation procedures. Storage medium (EP-II^® ) cultures for right eyes were included for the period between July 2008 and December 2017. The following donor characteristics were collected: age, sex, cause of death, history of cataract surgery, death-to-enucleation interval, death-to-preservation interval, and endothelial cell density (ECD). Donor characteristics were compared between MRSA and non-MRSA contamination groups. Odds ratios (ORs) for donor-related risk factors for MRSA contamination were determined using logistic regression.

RESULTS

In total, 370 storage medium samples were examined; 222 were positive for bacterial cultures (60.0%) and 36 were MRSA-positive (9.7%). Donor age was significantly higher in the MRSA contamination group than in the non-MRSA contamination group (86.1 ± 9.5 years vs 75.9 ± 15.9 years, P < 0.001). Univariate logistic regression analysis showed that MRSA contamination risk factors were older age (OR = 1.07; 95% confidence interval [95% CI]: 1.03-1.11) and decreased ECD (OR = 0.9993; 95% CI: 0.9986-0.9992). The fully adjusted OR for every year of age as a risk factor for MRSA contamination was 1.07 (95% CI: 1.03-1.11).

CONCLUSIONS

Aging was a risk factor for MRSA contamination in storage medium. Careful pre-banking assessment of elderly donor corneas is needed to prevent intractable postoperative MRSA infection.

Microbial keratitis in corneal grafts: predisposing factors and outcomes

PurposeTo identify the nature of microbial keratitis in corneal grafts and the clinical outcomes at a tertiary hospital in the United Kingdom.Patients and methodsA retrospective case series of microbial keratitis in corneal grafts at the Royal Victoria Infirmary, Newcastle upon Tyne over a 17-year period (1997-2014).ResultsA total of 759 consecutive corneal grafts were identified from the Cornea Transplantation database. Of these, 59 episodes of microbial keratitis occurred in 41 eyes of 41 patients (5.4%; 19 male, 46.3%). Median patient age was 73 years (SD=19.4 years). The most common indication for corneal transplantation was bullous keratopathy (11/41, 26.8%). There were 34/59 (57.6%) episodes of culture-positive graft keratitis; Streptococcus pneumoniae and Staphylococcus aureus were each isolated in 5/34 (14.7%) culture-positive episodes. In all, 35/59 (59.3%) episodes of microbial keratitis occurred in 22 previously failed grafts and 3 de novo graft failures. Gram-negative keratitis was more likely to cause reduced BCVA after (χ²-test, P=0.02). Median graft duration was 49.5 months (SD=43.7 months). Failed grafts were significantly older (median 69 vs 27 months, P=0.009).ConclusionThis represents the longest published follow-up data on microbial keratitis and is the only of its kind in the United Kingdom. The incidence of 5.4% is comparable to that within the developed world. Graft age was significantly associated with graft failure in microbial keratitis; the ongoing risk of microbial keratitis warrants providing patients with long-term open access to hospital eye services.

Infectious crystalline keratopathy

Infectious crystalline keratopathy was first reported by Gorovoy and colleagues in 1983 when they identified bacteria colonizing a cornea after a penetrating keratoplasty. Subsequent cases have elaborated on the organisms responsible and the management outcomes. Patients present with a white or gray branching opacity originating from an epithelial defect, commonly after a penetrating keratoplasty. Local immunosuppression contributes to the quiescent nature and the limited inflammatory response associated with infectious crystalline keratopathy. Diagnosis of the infective pathogens may be difficult, with a corneal scraping often being too superficial to obtain an adequate specimen. A biofilm is present that advantages microorganism survival, reduces antibiotic bioavailability, and inhibits diagnostic microbial detection. Treatment begins with topical antimicrobials, initially broad spectrum and then targeted to microorganism sensitivity. Adjunctive therapies to enhance the efficacy of treatment include disruption of the microorganism biofilm by laser, intrastromal antibiotics, and keratectomy. In recalcitrant cases, or where corneal scarring ensues, corneal transplantation is required.

Pre-banking microbial contamination of donor conjunctiva and storage medium for penetrating keratoplasty

PURPOSE

The aims of this study were to investigate the incidence of positive donor tissue cultures before transfer to preservation medium (Optisol™-GS) for penetrating keratoplasty, to verify the efficacy of antibiotics contained in Optisol™-GS by examining the drug susceptibility and to assess the relationship between the results of our microbial assessments as well as donor factors and the incidence of contamination.

METHODS

We conducted a retrospective, cross-sectional study using Juntendo Eye Bank records for all corneal transplantations. Two hundred donor conjunctiva harvestings and storage medium (EP-II^®) cultures were performed between July 2008 and June 2011. We analyzed the associations between donor factors (age, gender, history of cataract surgery, death-to-preservation interval, cause of death) and contamination rates using multivariate analysis by the generalized estimating equation model.

RESULTS

We obtained positive bacterial cultures from 154 of the 200 eyes (77.0%). The isolated bacteria were indigenous, such as coagulase-negative Staphylococci, Corynebacterium sp., and methicillin-resistant Staphylococcus aureus (MRSA). There was significant resistance to levofloxacin (18 eyes, 9.0%) and gentamicin (12 eyes, 6.0%), and no vancomycin-resistant bacteria were detected. The donor factors did not correlate with the prevalence of bacterial contamination in our criteria.

CONCLUSIONS

Pre-banking microbial assessment allows for microbial detection, bacterial susceptibility and resistance testing. This is useful for developing preservation mediums containing effective spectrum antibiotic agents for high quality control of corneal banking.

Microbial Keratitis After Penetrating Keratoplasty

PURPOSE

To report the incidence, microbiological profile, graft survival, and determining factors of microbial keratitis after penetrating keratoplasty (PK).

DESIGN

Observational case series.

METHODS

The study involved 51 patients (52 eyes) who were treated at a single tertiary referral center during a 10-year period. Retrospective chart review included medical records of all patients diagnosed with microbial keratitis after penetrating keratoplasty at the National Taiwan University Hospital between January 2000 and December 2009. The main outcome measures were incidence of graft infection, microbial profile, and graft survival status.

RESULTS

There were 871 PKs performed and 67 episodes in 52 eyes of culture-positive microbial keratitis during the study period. There were 32 infectious episodes (47.8%) in the first year post-PK and 35 episodes (52.2%) after the first year post-PK. Forty-four gram-positive bacterial isolates (57.9%), 17 gram-negative bacterial isolates (22.4%), and 15 fungal isolates (19.7%) were found. Twenty-three (34.3%) grafts remained clear after the infection episode with a mean follow-up of 1127 days (range, 25-3962 days). There was no difference in graft survival rate regarding the original indication of PK or offending pathogen. Suture-related infection was associated with decreased risk of graft failure (P = .02), while the factor associated with increased risk of graft failure was usage of antiglaucoma agents (P = .01).

CONCLUSION

Infectious keratitis after penetrating keratoplasty leads to a high graft failure rate. Such complications can occur before or after the first year post-PK.

Shifting trends in microbial keratitis following penetrating keratoplasty in Taiwan

To investigate the clinical and microbiological profiles from microbial keratitis following penetrating keratoplasty (PKP) in a tertiary referral center in Taiwan, the medical records of 648 consecutive patients (648 eyes) undergoing PKP between January 2003 and December 2007 were retrospectively reviewed. Patients who subsequently sustained microbial keratitis were enrolled and analyzed for potential risk factors, clinical manifestations, microbiological profiles, complications, graft survival, and final visual outcome. A total number of 42 corneal graft infections (6.5%) were recruited. Mean interval between corneal transplantation and graft infection was 12 ± 9.5 months. Potential risk factors included suture-related problems (31.0%), lid abnormalities (23.8%), persistent epithelial defect (23.8%), contact lens use (14.3%), dry eye (11.9%), and prior rejection episodes (4.8%). Lesions were discovered mostly at the donor-recipient junction ([DRJ] 45.2%). Positive cultures were identified in all of the morbid eyes, of which Pseudomonas aeruginosa was the most common pathogen (38.1%). Despite mandatory hospitalization and topical fortified antibiotics management, complications ensued such as graft failure (71.4%), hypopyon (21.4%), corneal perforation (14.3%), wound dehiscence (11.9%), and endophthalmitis (4.8%). The visual outcome was dismal that graft clarity was achieved in only 12 eyes (28.6%), and that final visual acuity deteriorated to less than 20/200 in 28 eyes (66.7%). In conclusion, microbial keratitis following PKP is a devastating event that severely impairs graft survival rate and postoperative visual outcome which usually occur within the first postoperative year. The incidence of post-PKP microbial keratitis has generally decreased in recent years whilst P. aeroginosa prevails as the leading cause of graft infection in our hospital. Close follow-up by ophthalmologists and elevated self-awareness of patients for at least one year are always encouraged to prevent late-onset infection.

A comparative, retrospective, observational study of the clinical and microbiological profiles of post-penetrating keratoplasty keratitis

Infectious keratitis after penetrating keratoplasty (PK) is a devastating condition that may result in graft failure and poor visual outcome. In this study, we retrospectively reviewed the medical records of patients who underwent PK between 2009 and 2014, and recorded those who developed infectious keratitis. We compared the predisposing factors and organisms isolated to those identified in our previous study, conducted between 1989 and 1994. The incidence of post-PK infectious keratitis decreased from 11.6% (41 out of 354 cases, 1989–1994) to 6.5% (9 out of 138 cases, 2009–2014). Graft epithelial defect and suture-related problems remained the leading two risk factors of infectious keratitis after PK. Gram-positive and Gram-negative bacterial infection decreased from 58.5% and 46.3% to 11.1% and 22.2%, respectively (P = 0.023 and P = 0.271). In contrast, fungus infection increased from 9.8% to 66.7% (P = 0.001); fungi have become the major pathogen for post-PK infectious keratitis. In conclusion, while the incidence of post-PK infectious keratitis has decreased over time, the number and frequency of fungal infections have significantly increased in the recent study period. Clinicians should be aware of the shifting trend in pathogens involved in post-PK infectious keratitis.

Role of steroids in the treatment of bacterial keratitis

Bacterial keratitis can lead to severe visual impairment from corneal ulceration, subsequent scarring, and possible perforation. The mainstay of treatment is topical antibiotics, whereas the use of adjunctive topical corticosteroid drops remains a matter of debate. Herein, we review the rationale for and against the use of topical corticosteroids and we assess their effectiveness and safety in the published randomized controlled trials that have evaluated their role as adjunctive therapy for bacterial corneal ulcers. In the largest study to date, the Steroids for Corneal Ulcers Trial, topical corticosteroid drops were neither helpful nor harmful for the 500 participants as a whole. However, subgroup analyses suggested that topical corticosteroids may be beneficial upon early administration (within 2–3 days after starting antibiotics) for more central corneal ulcers with poorer vision at presentation, for invasive Pseudomonas strains, and for non-Nocardia ulcers. These results are discussed within the limitations of the study.

Factors Affecting Treatment Outcome of Graft Infection Following Penetrating Keratoplasty

Purpose

To evaluate the factors affecting treatment outcome of graft infection following penetrating keratoplasty (PKP).

Methods

In this retrospective study, 28 patients who underwent PKP between January 2005 and January 2013 and who were diagnosed with graft infection were classified into a treatment success group or a treatment failure group. Demographic and clinical characteristics, as well as the results of the microbiologic investigation, were analyzed and compared. A subsequent binary logistic regression analysis was performed to identify the prognostic factors affecting treatment outcome.

Results

Graft infection occurred at a mean of 38.29 ± 36.16 months (range, 1 to 96 months) after PKP. Seventeen patients developed bacterial keratitis, and 11 patients developed fungal keratitis. Overall, of the 28 patients, nine (32.1%) were classified in the treatment failure group. Multivariate analysis identified pre-existing graft failure (p = 0.019), interval longer than 72 hours between donor death and PKP (p = 0.010), and fungal infection (p = 0.026) as significant risk factors for treatment failure.

Conclusions

Pre-existing graft failure, extended interval between donor death and PKP, and fungal infection were important risk factors for treatment failure of graft infection following PKP.

[Purulent corneal ulcers: etiology, pathogenesis, classification]

Advanced purulent corneal ulcer, as well as abscess, is a serious vision-threatening condition notable for its fulminant course and possible loss of the eye due to endophthalmitis. Its leading causes, pathogenesis, and classifications are described and analyzed in this paper.

Clinical and microbiological profile of post-penetrating keratoplasty infectious keratitis in failed and clear grafts

PURPOSE

To comparatively evaluate the clinical and microbiological profiles and treatment outcome of cases with post-penetrating keratoplasty (PK) infectious keratitis in failed and clear grafts.

DESIGN

Retrospective, matched cohort study.

METHODS

All cases of infectious keratitis following penetrating keratoplasty admitted to the Royal Victorian Eye and Ear Hospital, Melbourne, between January 1998 and December 2008 were identified through a retrospective medical chart review. Cases without any surface sutures were selected and divided into 2 groups, microbial keratitis with pre-existing graft failure and microbial keratitis in clear graft on presentation. Demographic, clinical, and microbiological profiles of cases in both groups were analyzed and compared.

RESULTS

Patients in the failed-graft group were older (P = .004) and had an early onset of graft infection (P = .049), compared with patients in the clear-graft group. All patients in the failed-graft group were on long-term corticosteroid drops at the time of presentation (vs 76% in clear-graft group; P = .005). Moraxella sp was more frequently isolated in the failed-graft group (30.4%) compared with the clear-graft group (8%). A higher number of cases in the clear-graft group required surgical intervention in the form of corneal gluing and therapeutic corneal transplantation compared with the failed-graft group (P = .03).

CONCLUSIONS

Prolonged use of corticosteroid eye drops is a major risk factor for the occurrence of postkeratoplasty infectious keratitis in failed and clear grafts. Infections in failed grafts occur earlier as compared to clear grafts, and indolent organisms like Moraxella are prevalent in patients with failed grafts in Australia.

Microbial keratitis after penetrating keratoplasty: impact of sutures

PURPOSE

To determine the impact of presence or absence of sutures in cases with post-penetrating keratoplasty (PKP) microbial keratitis.

DESIGN

A 10-year retrospective chart review of post-PKP patients admitted with microbial keratitis at the Royal Victorian Eye and Ear Hospital, Melbourne, between January 1998 and December 2008 was undertaken.

METHODS

Patients were categorized in 2 groups, "sutures present" and "sutures absent." Main parameters evaluated were clinical and microbiological profile and treatment outcome.

RESULTS

One hundred and twenty-two episodes of microbial keratitis were noted in 101 patients: 71 (58.2%) with sutures present and 51 (41.8%) with sutures absent. Overall, pseudophakic bullous keratopathy was the most common indication for keratoplasty (P=.92). Ocular surface disorder was the commonest risk factor associated with the occurrence of infection in both groups (P=.17). Infections caused by Moraxella sp. (P=.001) were significantly more common in the "sutures absent" group. Surgical interventions were required for 47 episodes (39%), with corneal gluing performed in significantly higher number of cases in the "sutures absent" group (40% vs 15%; P=.05). Multivariate analyses did not reveal any significant associations. Final mean visual acuity outcome was poorer in the "sutures absent" group (logMAR 2.10 ± 0.92 vs 1.76 ± 0.96; P=.04).

CONCLUSIONS

Corneal graft infections, in the presence and absence of sutures, share similar indications and risk factors. However, infections caused by indolent microorganisms were more prevalent in grafts without sutures. This group of patients required a higher number of surgical interventions in the form of corneal gluing and the overall visual outcome was poor.

Incidence, occurrence rate, and characteristics of suture-related corneal infections after penetrating keratoplasty

PURPOSE

To report the incidence, occurrence rate, and characteristics of suture-related infections after penetrating keratoplasty (PK).

METHODS

Patients who underwent PK at our institution between January 1, 2002, and July 1, 2006, were cross-referenced with patients diagnosed with corneal infections between January 1, 2002, and July 1, 2007. All patient charts were reviewed retrospectively for occurrence of suture-related infections, duration of follow-up, and clinical characteristics.

RESULTS

Of the 487 PKs performed in 412 patients, 22 eyes of 22 patients developed postoperative corneal infections. Of these, 5 eyes were identified as having suture-related graft infections, yielding an occurrence rate of 1.0%. The average follow-up was 3.46 years per PK, yielding an incidence of 2.96 infections per 1000 PK-years. The mean interval from surgery to infection was 8 months (range: 3-23 months). All culprit sutures were in the interpalpebral zone. No patients were using topical antibiotics at the time of infection, and all patients were using topical corticosteroid drops. Cultured organisms included Staphylococcus aureus (3 cases), coagulase-negative Staphylcoccus (1 case), and S. viridans (1 case). In 2 patients with isolated corneal involvement, topical moxifloxacin was initiated, and the patients responded favorably. In 3 patients with corneal infection and an associated hypopyon or endophthalmitis, vitreous biopsy, intravitreal injections of antibiotics, and fortified topical antibiotics were used. One patient required a repeat PK as a result of the infection. Two eyes eventually became phthisical.

CONCLUSIONS

The rate of suture-related infections after PK may be lower than previously reported. In our patients, suture-related infections all occurred within the first 2 years after surgery, and some of them resulted in significant morbidity, underscoring the importance of patient identification of symptoms and early clinical recognition.

Microbial keratitis following corneal transplantation

PURPOSE

To determine the predisposing risk factors and analyse the clinical and microbiological profiles of microbial keratitis following corneal transplantation.

METHODS

A retrospective analysis was done of hospital records of all patients who presented with microbial keratitis in the corneal graft between July 2000 and June 2005 at the Corneal Unit of Royal Victorian Eye and Ear Hospital, Melbourne, Australia.

RESULTS

Eighty-one episodes of infection were identified in 62 patients over a 5-year period. Thirteen patients had multiple episodes of infection. The mean age of the patients was 70 +/- 16 years (range: 22-92 years). The median time interval between the graft and infection was 17 months (range: 6 days to 385 months). Twenty-two (35%) episodes of primary infection were related to sutures. The associated predisposing risk factors were failed graft (40%), dry eye (18%), Herpes simplex keratitis (8%), and ocular surface disease (8%). Forty-seven (76%) cases were culture positive for bacteria. Ten cases were positive for Herpes simplex virus (HSV) during presentation.

CONCLUSION

Failed graft is a long-term risk factor for graft infection in addition to ocular surface disease and H. simplex keratitis. All the predisposing risk factors increase the risk of recurrent graft infection.

Bacterial Keratitis after Penetrating Keratoplasty

PURPOSE

To determine the incidence, microbiological profile, graft survival, and factors influencing graft survival after the development of bacterial keratitis after penetrating keratoplasty (PK).

DESIGN

Retrospective case series.

PARTICIPANTS

One hundred two patients (102 eyes) treated at a single center during a 5-year period.

METHODS

Retrospective review of the medical records of every patient treated for culture-positive keratitis between January 1, 1998 and December 31, 2002 who previously had undergone penetrating keratoplasty at the King Khaled Eye Specialist Hospital.

MAIN OUTCOME MEASURES

Graft survival and visual outcome.

RESULTS

There were 2103 PKs performed and 102 (4.9%) cases of culture-positive keratitis during the study period. There were 168 bacterial isolates, of which 140 (83.3%) were gram positive, 28 (16.7%) were gram negative, and 1 (0.6%) was acid fast. Only 38 (37.3%) grafts remained clear after a mean follow-up of 985 days (range, 82-2284). The best graft survival was in eyes with PK for keratoconus (83.7%), whereas the poorest grat survival was for previously failed grafts (5.6%). By Kaplan-Meier analysis, there was an immediate steep decline in graft survival to 54.9%, followed by a slow decline to 47.2% by 1 year and 35.8% after 4 years. Factors associated with an increased risk of graft failure were the surgical indication for PK (P<0.001), increasing patient age (P = 0.004), smaller donor (P = 0.001) and recipient (P = 0.0003) graft size, history of previous microbial keratitis (P = 0.02) or endothelial rejection episodes (P = 0.02), and coexisting glaucoma (P = 0.001). The visual outcome was > or =20/40 in only 8 (8.2%) eyes and better than 20/200 in only 21 (21.6%) eyes.

CONCLUSION

The development of bacterial keratitis after PK is a serious complication that is associated with a high incidence of graft failure and poor visual outcome.

Bilateral simultaneous Achromobacter xylosoxidans keratitis following penetrating keratoplasty

We report a case of severe bilateral simultaneous Achromobacter xylosoxidans keratitis following penetrating keratoplasty (PKP) in a patient with graft-versus-host disease. The predisposing factors, clinical features, treatment options, and final visual outcome are reviewed. To our knowledge, this is the first report of bilateral A xylosoxidans keratitis following PKP.

Infectious keratitis following keratoplasty

Infectious keratitis following corneal transplantation is one of the leading causes of failure of a corneal graft. The incidence of graft infection is variable, with developing countries having a higher incidence. The majority of the graft infections occur within 1 year of the corneal transplantation. Suture-related problems and persistent epithelial defect are the most common risk factors predisposing to graft infection. Pneumococcus species and Staphylococcus aureus have been found to be the commonest microorganisms in the developed world, whereas Staphylococcus epidermidis is the most often detected microorganism in corneal graft infection in the developing world. The early identification of predisposing risk factors in patients and their appropriate management at the earliest may prevent the occurrence of graft infection and might improve graft survival. Visual prognosis in eyes with post-keratoplasty graft infection is poor even after optimal therapy and there is a high rate of graft decompensation.

Microbial keratitis following corneal transplantation

PURPOSE

To study clinical and microbiologic characteristics of corneal infections following penetrating keratoplasty (PK).

DESIGN

Retrospective case series.

METHODS

Medical records of patients who presented to Duke University Eye Center from January 1, 1999 to July 1, 2005 with microbial keratitis after PK were reviewed.

RESULTS

Forty-four corneal graft infections were reviewed. Mean interval between PK and infection was 26.3 months. Associated conditions included broken or loose sutures (10, 22.7%) and topical corticosteroids (34, 77.3%). Staphylococcal (12, 20.7%) and Pseudomonal (7, 12.1%) species were common pathogens, and fungal species accounted for eight (18.2%) infections. Twelve patients (27.3%) had polymicrobial infections. Thirteen patients (29.5%) underwent repeat PK. Mean postinfection visual acuity at last follow-up was 20/400.

CONCLUSIONS

Microbial infections within corneal grafts can occur anytime in the postoperative course and are associated with broken sutures and the use of topical corticosteroids. The diversity of pathogenic organisms, antibiotic resistance, and the potential for poor outcomes supports aggressive management of these infections.

Successful Topical Application of a New Antifungal Agent, Micafungin, in the Treatment of Refractory Fungal Corneal Ulcers

PURPOSE

To report the efficacy of topical application of a new antifungal agent, micafungin (MCFG), in the treatment of yeast-related corneal ulcers.

DESIGN

Noncomparative interventional case reports.

PARTICIPANTS

Three patients with yeast-related corneal ulcer after keratoplasty recalcitrant to conventional antifungal treatment for 4 weeks were recruited in this study.

METHODS

Topical 0.1% antifungal MCFG eye drops were applied in 3 patients with yeast-related corneal ulcer every hour while awake until epithelialization. After epithelialization, the frequency of eye drops was reduced to 5 times a day. MCFG eye drops were discontinued 1 month after the disappearance of stromal infiltration in each case. The patients underwent best corrected visual acuity (BCVA) measurements, slit-lamp examination, fluorescein-dye staining, and anterior segment photography. Corneal scrapings and cultures of surgical materials were also performed.

MAIN OUTCOME MEASURES

Changes in ulcer size, stromal infiltration, fluorescein dye staining, and BCVA were looked for.

RESULTS

All corneal ulcers epithelialized within 14 days after commencement of application of 0.1% MCFG eye drops. Yeasts were detected from corneal smears in all eyes. Two cases revealed positive culture isolates for Candida albicans and Candida parapsilosis. No recurrence of fungal keratitis was observed in any of the cases throughout the follow-up periods.

CONCLUSION

Topical 0.1% MCFG eye drops seem to be an effective and a promising option in the treatment of refractory yeast-related corneal ulcers.

Survival of Pseudomonas aeruginosa in M-K preserved corneas

AIM

To present seven eyes of suspected donor to host transmitted Pseudomonas sp corneal graft infection after corneal and scleral graft leading to corneal melting within 24 hours, in a span of 10 months.

METHODS

Case series. Seven eyes, operated for either penetrating or lamellar keratoplasty or scleral patch graft for different indications and which developed massive corneal/corneoscleral infection within 24 hours, were studied prospectively.

RESULTS

Pseudomonas aeruginosa, resistant to almost all antibiotics except polymyxin B in all and vancomycin in two, was identified as the causative organism from all the specimens obtained from the infected graft.

CONCLUSION

Post-keratoplasty infection is a disaster. The source of early infection is invariably iatrogenic. Use of empirical antibiotics in the media is not always sufficient to prevent such infection. Thus, measures must be taken in the form of strict maintenance of asepsis and revision of antibiotics added to the storage medium. Further, early recognition and energetic therapy for such infection could reduce the ophthalmic morbidity.

Therapeutic penetrating keratoplasty for microbial keratitis in Taiwan from 1987 to 2001

PURPOSE

To determine the surgical outcomes of therapeutic penetrating keratoplasty (PKP) and its role in the management of microbial keratitis.

DESIGN

Interventional case series.

METHODS

We retrospectively performed a chart review of the hospital records of all 151 patients undergoing therapeutic PKP for culture-proven microbial keratitis at the National Taiwan University Hospital during a 14 year-period (1987-2001). Patients were divided into three categories: (1) bacterial keratitis; (2) fungal keratitis; and (3) acanthamoebic keratitis. Each of the following criteria was evaluated: (1) graft clarity 1 month and 1 year postoperatively; (2) cure of the disease; and (3) anatomical success rate.

RESULTS

A total of 108 therapeutic PKP met the criteria. Therapeutic PKP eradicated the infection in 37/41 of patients with bacterial keratitis, 36/52 of patients with fungal keratitis, and 13/15 of patients with acanthamoebic keratitis. 22/32 of grafts of bacterial keratitis, 20/39 of fungal keratitis, and 11/14 of acanthamoebic keratitis remained clear at 1 year postoperatively. A higher percentage of graft clarity at 1 year postoperatively was achieved in all three categories when grafts were 8.5 mm or less compared with larger grafts. All five patients with secondary endophthalmitis observed at the time of therapeutic PKP experienced a progression of infection despite aggressive surgical treatment, and had to be enucleated.

CONCLUSIONS

Therapeutic PKP is valuable in the management of microbial keratitis that is unresponsive to medical therapy. A higher percentage of clear graft was found when grafts were smaller in all three categories. Surgical results are worse for patients with fungal keratitis, regardless of graft clarity, anatomical success, or infection eradication rate.

Candida parapsilosis keratitis

PURPOSE

To present clinical, microbiologic, and histopathologic features of keratitis due to Candida parapsilosis.

METHODS

Clinicomicrobiologic evaluation of four patients (four eyes) with culture-proven C. parapsilosis keratitis. The patients were evaluated for symptoms, visual acuity, clinical observations, microbiologic examination of corneal scrapings, and pathologic examination of corneal buttons.

RESULTS

Three cases were observed after penetrating keratoplasty, and one case occurred after inhalation of corticosteroids. Clinical presentation of C. parapsilosis keratitis showed a great diversity. There was one case of crystalline keratopathy and three cases of suppurative corneal infiltrate. Histopathology of corneal buttons showed interlamellar accumulations of yeast. Medical treatment included topical amphotericin B and systemic triazoles. Penetrating keratoplasty was required in three patients.

CONCLUSION

Risk factors for C. parapsilosis keratitis may include corticosteroid use and prior corneal transplantation. The prognosis of C. parapsilosis keratitis with antifungal and surgical therapy may vary from good visual outcome to intraocular extension with phthisis bulbi.