Spectral domain anterior segment optical coherence tomography in microbial keratitis

Purpose

To investigate the spectral domain anterior segment optical coherence tomography (SDAS-OCT) patterns in microbial keratitis (fungal and bacterial keratitis).

Design

Prospective, cross-sectional, observational study.

Methods

Twenty eyes of 20 patients with proven fungal and bacterial microbial keratitis, at different stages of the disease, underwent SDAS-OCT imaging.

Results

Eight eyes presented with proven bacterial keratitis (3 Staphylococcus Aureus, 2 Pseudomonas Aeruginosa and 3 Staphylococcus Epidermidis). Twelve eyes presented with proven fungal keratitis of Aspergillus species. Twelve different SDAS-OCT presentations of fungal and bacterial keratitis were found in this study. Our findings in fungal keratitis grasped two unique patterns of early localized and diffuse necrotic stromal cystic spaces.

Conclusion

SDAS-OCT imaging provided a range of characteristic patterns that could be used as an additional tool in diagnosis and management of bacterial and fungal microbial keratitis.     

Clinical review of corneal ulcers resulting in evisceration and enucleation in elderly population

Purpose

To identify the associated factors and study the clinical and microbiological characteristics of corneal ulcers resulting in evisceration and enucleation in elderly patients in a tertiary care hospital.

Methods

A review of all patients who required evisceration or enucleation due to microbial keratitis at the Royal Victorian Eye and Ear Hospital, Melbourne, Australia between July 1998 and November 2007 was performed. Of these, patients more than 60 years of age were included in the study for analysis.

Results

Forty-seven patients with microbial keratitis were included in the study. The mean age of patients was 81?±?9.39 years. Major ocular factors associated were glaucoma (49%), persistent corneal epithelial defect (38%) and use of corticosteroid eye drops (23%). Most common associated systemic factor was rheumatoid arthritis (36%). The indications for evisceration or enucleation were extensive non-healing microbial keratitis (22/47) and corneal perforation secondary to microbial keratitis (17/47). Pseudomonas aeruginosa was the most common pathogen, present in 15 patients, and more than 45% of the strains tested were resistant to chloramphenicol.

Conclusions

Corneal ulcers that result in the loss of eye in elderly population are frequently associated with glaucoma and persistent epithelial defects. The majority of these cases have non-healing microbial keratitis caused by Pseudomonas aeruginosa.     

Review of epidemiological features, microbiological diagnosis and treatment outcome of microbial keratitis: Experience of over a decade

Purpose:

To review the epidemiological characteristics, microbiological profile, and treatment outcome of patients with suspected microbial keratitis.

Materials and Methods:

Retrospective analysis of a non-comparative series from the database was done. All the patients presenting with corneal stromal infiltrate underwent standard microbiologic evaluation of their corneal scrapings, and smear and culture-guided antimicrobial therapy.

Results:

Out of 5897 suspected cases of microbial keratitis 3563 (60.4%) were culture-proven (bacterial – 1849, 51.9%; fungal – 1360, 38.2%; Acanthamoeba – 86, 2.4%; mixed – 268, 7.5%). Patients with agriculture-based activities were at 1.33 times (CI 1.16–1.51) greater risk of developing microbial keratitis and patients with ocular trauma were 5.33 times (CI 6.41–6.44) more likely to develop microbial keratitis. Potassium hydroxide with calcofluor white was most sensitive for detecting fungi (90.6%) and Acanthamoeba (84.0%) in corneal scrapings, however, Gram stain had a low sensitivity of 56.6% in detection of bacteria. Majority of the bacterial infections were caused by Staphylococcus epidermidis (42.3%) and Fusarium species (36.6%) was the leading cause of fungal infections. A significantly larger number of patients (691/1360, 50.8%) with fungal keratitis required surgical intervention compared to bacterial (799/1849, 43.2%) and Acanthamoeba (15/86, 17.4%) keratitis. Corneal healed scar was achieved in 75.5%, 64.8%, and 90.0% of patients with bacterial, fungal, and Acanthamoeba keratitis respectively.

Conclusions:

While diagnostic and treatment modalities are well in place the final outcome is suboptimal in fungal keratitis. With more effective treatment available for bacterial and Acanthamoeba keratitis, the treatment of fungal keratitis is truly a challenge.     

Atypical Herpes simplex keratitis (HSK) presenting as a perforated corneal ulcer with a large infiltrate in a contact lens wearer: multinucleated giant cells in the Giemsa smear offered a clue to the diagnosis

Purpose  

To report a case of atypical herpes simplex keratitis initially diagnosed as bacterial keratitis, in a contact lens wearer.     

Is Microsporidial keratitis an emerging cause of stromal keratitis? – a case series study

Background  

Microsporidial keratitis is a rare cause of stromal keratitis. We present a series of five cases of microsporidial keratitis from a single centre in southern India with microbiologic and histopathologic features.     

Microbial keratitis in Stevens-Johnson syndrome: Clinical and microbiological profile

Purpose

To study the clinical and microbiological profile of microbial keratitis in Stevens-Johnson syndrome (SJS).

Incidence and microbiological profile of mycotic keratitis in a tertiary care eye hospital: A retrospective analysis

Purpose

To determine the incidence and microbiological profile of mycotic keratitis seen at a tertiary care eye hospital.

Materials and methods

A retrospective review of microbiology records of patients presenting with suspected microbial keratitis seen between January 2006 and December 2009 was performed. Patients with positive fungal cultures were further analyzed for the type of fungus isolated and associated bacterial pathogens.

Results

Microbiology records of 2300 patients with suspected microbial keratitis were reviewed. A microbiological diagnosis of mycotic keratitis was established in 87 (3.8%) patients over a four year period based on positive fungal cultures. The yearly incidence of mycotic keratitis was 3.2% (2006), 4.9% (2007), 3.3% (2008) and 3.6% (2009). Filamentous fungi were isolated more often than yeasts. Aspergillus species followed by Fusarium species and Trichophyton species were the commonest filamentous fungi isolated while Candida albicans was the most frequently encountered yeast. Mixed infections due to fungal and bacterial pathogens were seen in 25/87 (28.7%) patients.

Conclusion

Cumulative incidence of mycotic keratitis was 3.8% over a four year period. Aspergillus species and Candida albicans were the most frequent pathogenic organisms causing mycotic keratitis in this part of the world. Mixed infections were seen in 28.7% of the patients. Knowledge of the “local” etiology within a region may be valuable in the management of mycotic keratitis in instituting an empirical therapy, especially when facilities for microscopy, cultures and antifungal susceptibility are not readily available. The baseline information presented will also be helpful in the planning of a corneal ulcer management strategy and for future studies on mycotic keratitis.     

Hyeropic shift after LASIK induced Diffuse lamellar keratitis

Background  

Diffuse lamellar keratitis (DLK) is a relatively new syndrome that is increasingly being reported after LASIK. We have observed that a hyperopic shift may be associated with the occurrence of this diffuse lamellar keratitis.     

Detection of ICP0 protein in tear fluid of individuals with active herpetic epithelial keratitis

Purpose  

Infected cell protein 0 (ICP0) has been detected in the tear fluid of rabbits with herpetic keratitis. Here, we investigated whether ICP0 of herpes simplex virus 1 is detectable in the tear fluid of patients with herpetic epithelial keratitis.     

Antimicrobial management of presumed microbial keratitis: guidelines for treatment of central and peripheral ulcers

AIMS—To determine the quantitative relation between the major risk factors for microbial keratitis of previous ocular surface disease and contact lens wear and central and peripheral infiltration, often associated with ulceration, in order to establish a rational chemotherapeutic management algorithm.
METHODS—Data from 55 patients were collected over a 10 month period. All cases of presumed microbial keratitis where corneal scrapes had been subjected to microbiological examination were included. Risk factor data and laboratory outcome were recorded. Antimicrobial regimens used to treat each patient were documented.
RESULTS—57 episodes of presumed microbial keratitis were identified from 55 patients, 24 male and 31 female. There were 30 central infiltrates and 27 peripheral infiltrates of which 28 were culture positive (73% of central infiltrates, 22% of peripheral infiltrates). 26 patients had worn contact lenses of whom 12 had culture positive scrapes (9/14 for central infiltrates, 3/12 for peripheral infiltrates). 31 patients had an ocular surface disease of whom five previous herpes simplex virus keratitis patients developed secondary bacterial infection. Anterior chamber activity and an infiltrate size  4 mm² were more common with culture positive central infiltrates than peripheral infiltrates (χ² test = 11.98, p<0.001).
CONCLUSIONS—Predisposing factors for "presumed" microbial keratitis, either central or peripheral, were: ocular surface disease (26/57 = 45.6%), contact lens wear (26/57 = 45.6%), and previous trauma (5/57 = 8.8%). Larger ulceration (4 mm²) with inflammation was more often associated with positive culture results for central infiltration. None of these four variables (contact lens wear, ocular surface disease, ulcer size, anterior chamber activity) were of intrinsic value in predicting if a peripheral infiltrate would yield identifiable micro-organisms. Successful management of presumed microbial keratitis is aided by a logical approach to therapy, with the use of a defined algorithm of first and second line broad spectrum antimicrobials, for application at each stage of the investigative and treatment process considering central and peripheral infiltration separately.

Keywords: ulcerative keratitis; antimicrobials; ulcers     

Clinical presentation and morbidity of contact lens–associated microbial keratitis: a retrospective study

Purpose

To investigate the clinical presentation, isolated organism, treatment, and morbidity of contact lens–associated microbial keratitis needing hospitalization.

Methods

This retrospective study included all consecutive patients with contact lens–associated microbial keratitis hospitalized in the Rotterdam Eye Hospital from January 1, 2005, to December 31, 2009. All data regarding epidemiological characteristics, clinical presentation, isolated organism, and treatment were collected from medical records.

Results

There were 109 cases (108 patients) of contact lens–associated microbial keratitis hospitalized during the study period. Mean age was 33.3?±?15.4 (SD) years. Pseudomonas aeruginosa was the most frequently isolated microorganism (68.8 %), with minor resistance to gentamicin (2.7 %) and ofloxacin (1.3 %). At time of presentation, best corrected visual acuity (BCVA) was very poor, with the largest proportion of patients (65.1 %) seeing worse than 0.05 Snellen. After intensive treatment, the visual outcome improved considerably, with the largest proportion (67.0 %) achieving a BCVA?≥?0.7 Snellen. Low BCVA at admission was significantly associated with a worse final BCVA. A total of 22 patients (20.2 %) required corneal transplantation (three emergency cases). Larger size of stromal infiltrate was significantly associated with the need for corneal transplantation.

Conclusion

Microbial keratitis is a serious complication of contact lens wear, with approximately one out of five hospitalized cases requiring corneal transplantation. Ofloxacin, or a combination of gentamicin and cephazolin, still appear to be excellent first-choice therapies in the Netherlands, as little resistance has developed to these antibiotics.     

Morphological changes of corneal subepithelial nerve plexus in different types of herpetic keratitis

Purpose  

We investigated by in vivo confocal microscopy alterations in the subepithelial nerve plexus in different types of herpes simplex keratitis (HSK).     

Evaluation of antibacterial efficacy of photo-activated riboflavin using ultraviolet light (UVA)

Background  

To evaluate the antibacterial efficacy of photo-activated riboflavin using Ultraviolet A (UVA) on three bacterial strains commonly detected in keratitis.     

UVA-riboflavin photochemical therapy of bacterial keratitis: a pilot study

Background  

The aim of this work as to investigate the photochemical interaction used in corneal crosslinking (CXL) as the primary therapy for bacterial keratitis.     

Herpes simplex virus bullous keratitis misdiagnosed as a case of pseudophakic bullous keratopathy with secondary glaucoma: an unusual presentation

Purpose  

To report an unusual case of herpetic bullous keratitis misdiagnosed as a case of pseudophakic bullous keratopathy with secondary glaucoma.     

Staphylolysin is an effective therapeutic agent for <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> experimental keratitis

Background  

Therapy of S. aureus keratitis is increasingly challenging due to emerging resistant strains. Staphylolysin (LasA protease) is a staphylolytic endopeptidase secreted by Pseudomonas aeruginosa. The purpose of the current study was to study the effect of treatment with staphylolysin on experimental keratitis caused by various Staphylococcus aureus strains.     

Molecular characterization, biofilm analysis and experimental biofouling study of Fusarium isolates from recent cases of fungal keratitis in New York State

Background  

To characterize Fusarium isolates from recent cases of fungal keratitis in contact lens wearers, and to investigate fungal association with MoistureLoc solution.     

Microbiological findings and predisposing risk factors in corneal ulcers

Background  

To identify the current bacterial spectrum, the specific resistances to commonly used antibiotics, and the predisposing risk factors causing bacterial keratitis.     

Risk factors for contact lens-related microbial keratitis in Singapore

Purpose:

To investigate independent risk factors for contact lens-related microbial keratitis in Singapore and estimate their impact on disease load.

Methods:

Cases were contact lens wearers presenting to Singapore National Eye Centre with microbial keratitis between 2008 and 2010. Community contact lens wearers were recruited as controls. All wearers completed a previously validated questionnaire describing contact lens wear history, hygiene and compliance habits, and demographics. Risk factors significant in univariate analysis (P<0.2) were evaluated in a multivariate model.

Results:

In all, 58 cases of microbial keratitis and 152 contemporaneous controls were identified. When controlling for other variables, Chinese had a 7 × lower risk compared with other races (95% CI: 2.3–21.3, P=0.001). Those aged between 25 and 44 years were at 3 × increased risk compared with younger wearers (95% CI: 1.1–9.6, P=0.04). Occasional overnight contact lens wear (less often than one night per week) was associated with a 4 × higher risk (95% CI: 1.2–15.4, P=0.03) compared with daily use. Not washing hands before handling was associated with a 13 × increased risk (95% CI: 1.9–84.8, P=0.008). Use of multipurpose solution A carried a 16 × higher risk compared with hydrogen peroxide (95% CI: 1.5–174.0, P=0.02). The combined PAR% for modifiable risk factors (occasional overnight wear, not washing of hands, and MPS A) was 82%.

Conclusions:

Consistent with previous findings, independent risk factors for contact lens-related microbial keratitis include poor hand hygiene, occasional overnight wear, and type of lens care solution. Prolonged overnight or extended contact lens use was infrequent in this population.     

Prospective comparison between conventional microbial work-up vs PCR in the diagnosis of fungal keratitis

Purpose

The PCR was compared with routine microbial studies for the detection of fungal pathogens in clinically suspected fungal keratitis.

Methods

A prospective nonrandomized study was undertaken at a tertiary eye care centre to evaluate 30 eyes of 30 patients with presumed fungal keratitis, both fresh and treated. Corneal scrapings were performed on each patient. The specimens were analysed by a semi-nested PCR assay using fungal-specific primers. PCR products were cloned and sequenced for identification, and compared with a conventional microbial work-up (smear and culture).

Results

Of the 30 samples, the PCR showed positivity in 93.3%, culture in 40%, and potassium hydroxide in 20%. Of the 28 PCR-positive cases, 12 were culture-positive and 16 were culture-negative. Two samples were both PCR and culture test negative. Culture-negative samples were PCR-positive in 16 of 18 (88.9%) cases. The PCR did not yield any false-negative findings in a culture-positive specimen. Both common and uncommon aetiologic fungi have been identified by DNA sequencing analysis.

Conclusion

The PCR was able to detect fungal DNA in a high proportion of culture-negative cases. Technical considerations of the PCR process include extraction of artifacts and amplification of non-pathogenic DNA. Nonetheless, our findings suggest that the PCR can be a useful adjunct to smear and culture in the rapid diagnosis of fungal keratitis, particularly in cases of failed detection from routine procedures.