Aetiology of suppurative corneal ulcers in Ghana and south India, and epidemiology of fungal keratitis

Causes and incidence of destructive eye procedures in north-eastern ghana

OBJECTIVE

To determine the causes and incidence of destructive ophthalmic procedures as seen at a major reference eye centre in northern Ghana

METHODS

Retrospective case series involving a review of surgical records of all evisceration and enucleation procedures done between January 2002 and December 2006 at the Bawku Hospital Eye Department. Information collected included basic demographic data, diagnosis, visual acuity at diagnosis and the eye affected. The aetiology responsible was determined from history, clinical examination and investigations as contained in the existing records. The primary clinical indications for evisceration were categorized into degenerative lesions, infections, trauma, neoplasms, and others. Statistical analysis was done using the Epi Info software.

RESULTS

A total of 337 eyes of 336 patients made up of 217 (64.6%) males and 119 (35.4%) females were removed during the study period. Mean age was 36.4 with a range of 1-90 years. Children under 15 years constituted 25.1% of whom 9.3% were under 5 years. The elderly (>/=60 years) comprised 26.3%. The most common cause of destructive procedure was endophthalmitis /panophthalmitis (47.9%), ocular injuries (23.2%), degenerative lesions (8.9%) and neoplasms (5.1%). Regarding neoplasms, females were more likely to be enucleated while the reverse was so for traumas (p=0.04 and p=0.02, Chi(2) test, respectively). Compared to the total number of surgeries done each year the crude incidence was computed at 26.6% per 1000 cases per year.

CONCLUSION

Most causes of destructive procedures in this part of Ghana are preventable and serious preventive strategies are needed to reverse this trend.

The etiology of infectious corneal ulceration in Sierra Leone

The microbial etiology of infectious corneal ulceration in Sierra Leone has been investigated. Patients either presenting to district health centers or encountered on rural surveillance expeditions with suspected infectious ulcerative keratitis were recruited into the study. Infectious corneal ulceration was defined as clinical evidence of corneal infection with epithelial defect with or without hypopyon. Cultures were obtained in a standard fashion and subsequent microbial analysis performed on all specimens. Seventy-three (73) cases of suspected infectious ulcerative keratitis were obtained between January 2005 and January 2006. The most commonly isolated organisms from microbial cultures of infected eyes were Gram-negative bacteria (45.2%), Gram-positive bacteria (37.0%), and fungal species (35.6%). Mixed bacterial and fungal organisms were isolated from ten eyes (13.7%) and no organisms were isolated from four eyes (5.5%). There is a high incidence of Gram-negative and fungal ulcerative keratitis in the population studied in Sierra Leone. Empirical therapy for corneal ulceration in this region should be aimed towards treatment of bacterial, fungal, and mixed infections.

A fungal pH-responsive signaling pathway regulating Aspergillus adaptation and invasion into the cornea

PURPOSE

To investigate the role of PalB and PacC, two components of a pH-responsive signal-transduction pathway of Aspergillus nidulans, during the pathogenesis of fungal infection of the cornea.

METHODS

Fungal strains included an A. nidulans wild-type isolate (A83), loss-of-function A. nidulans mutants of the palB (B7) or pacC (C6309) genes, and reconstituted genotypic strains (B7R and C6309R). Doubling times and radial growth rates were examined under neutral and acidic conditions. Corneal virulence was assessed ex vivo by topical inoculation of scarified porcine or human corneas with A. nidulans strains maintained in buffered medium until histologic examination after days 1, 3, and 5.

RESULTS

In vitro growth kinetics were similar for A. nidulans strains in liquid medium at pH 6.0 (P = 0.24) and 7.3 (P = 0.75). The pacC mutant C6309 grew more slowly (P < 0.001) on solid medium, whereas palB and pacC rescuants had growth kinetics comparable to those of the wild-type. Wild-type A. nidulans germinated on porcine corneas and produced hyphae that progressively invaded the stroma, reaching an average maximum penetration of 56% +/- 9% at 5 days after exposure. In contrast, hyphal invasion was significantly less by mutant strains B7 (P = 0.005) and C6309 (P = 0.003). Fungal penetration by C6309 was also significantly less than the wild-type (P = 0.0005) on explanted human corneas. Both fungal rescuants showed stromal invasion similar to the wild-type.

CONCLUSIONS

Corneal invasion by filamentous hyphae is attenuated by palB and pacC mutant strains of A. nidulans. The PacC pathway is involved in regulating fungal filamentation during ex vivo Aspergillus infection of the cornea.

Expression and potential role of major inflammatory cytokines in experimental keratomycosis

PURPOSE

The aim of this study was to investigate the expression and regulation of the four major inflammatory cytokines in fungal keratitis (FK) with the goal of further understanding its pathogenesis in order to develop more effective therapeutic approaches.

METHODS

Aspergillus fumigatus and Candida albicans were the corneal pathogens selected for this study to establish murine FK using epikeratophakia with the aid of corneal epithelium erasion. One, three, five, and seven days post-infection, the corneal lesions and inflammatory responses were observed by slit-lamp and histopathology, and the expressions of the four inflammatory cytokines, macrophage inflammatory protein-2 (MIP-2), cytokine-induced neutrophil chemoattractant (KC), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6), in the infected corneas were determined using reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). For the intervention experiment with neutralizing antibodies, the experimental mice were then injected subconjunctivally with 5 microl (2 ng/microl) MIP-2 or IL-1beta polyclonal antibody 1 h before and 24 h after surgery. Reestablishment of the FK murine model was performed following injection. Effects of MIP-2 or IL-1beta polyclonal antibody on the corneal diseases were observed by slit-lamp microscopy, histopathology, and ELISA.

RESULTS

Expression of MIP-2, KC, IL-1beta, and IL-6 was upregulated significantly in the infected group one, three, five, and seven days after surgery. Following treatment with an MIP-2 polyclonal antibody, the corneal clinical scores and inflammatory responses decreased, the MIP-2 protein levels were downregulated significantly (p<0.01), and the KC protein levels decreased slightly (p>0.05). Upon administration of IL-1beta polyclonal antibodies, the decrease in clinical scores, inflammatory responses, and protein levels of MIP-2 and KC was apparent at 1 and 3 days after infection (p<0.01).

CONCLUSIONS

A persistent, high level expression of MIP-2 and IL-1beta is an important and even major factor in the corneal pathogenesis of FK. Specific polyclonal neutralizing antibodies may be administered to inhibit the major chemokines and cytokines responsible for corneal damage thus effectively relieving the injury caused by FK.

Fungal Spectrum Identified by a New Slide Culture andIn VitroDrug Susceptibility Using Etest in Fungal Keratitis

PURPOSE

To investigate the spectrum of fungal species causing keratitis and to test antifungal drug susceptibility to each isolate using Etest.

METHODS

Microbial cultures were performed for patients who were clinically diagnosed with fungal keratitis between September 2002 and July 2004. Modified slide culture was established to identify the fungal species of the isolates. Etest (AB BIODISK, Solna, Sweden) was applied to determine the antifungal agent susceptibility of each isolate to itraconazole, fluconazole, and amphotericin B in vitro, respectively.

RESULTS

Among 73 eyes of 73 patients with clinical diagnosis of fungal keratitis, 61 strains of fungi were isolated from 61 eyes. The rate of positive culture was 81.3% of all cases. The spectrum of fungal species involved: 58 (95.1%) isolates of filamentous fungi, including the two most common genera-Fusarium (n = 33, 54.1%) and Aspergillus (n = 9, 14.8%),-followed by 16 (26.2%) isolates of other genera of filamentous fungi such as Alternaria (n = 3, 4.9%), Trichophyton (n = 3, 4.9%), Curvularia (n = 2, 3.3%), Chrysosporium (n = 2, 3.3%), Acremonium (n = 2, 3.3%), and Scedosporium (n = 1, 1.6%), 1 (1.6%) yeast of Candida, as well as two (3.3%) dimorphic fungi of Blastomyces and Sporothrix isolate each. Three filamentous fungi of the isolates failed to be identified according to the information provided by slide culture. The results of Etest showed that 20 (60.6%) isolates of Fusarium were susceptible to amphotericin B, whereas all of them were resistant to itraconazole and fluconazole. All nine (100%) isolates of Aspergillus were sensitive to itraconazole, whereas four (44.4%) of them were sensitive to amphotericin B, and only two (22.2%) of them were sensitive to fluconazole. Seventeen (89.5%), 13 (68.4%), and 10 (52.6%) isolates of the remaining 19 organisms were sensitive to amphotericin B, itraconazole, and fluconazole, respectively.

CONCLUSIONS

Fusarium and Aspergillus are the most frequent pathogenic organisms in causing fungal keratitis, whereas other species of fungi can also cause corneal infection. In vitro Etest for assessing antifungal drug susceptibility is a simple and practical method and may provide referential information for clinical consideration of choosing antifungal agents to treat fungal keratitis.

Retracted: Roles of Adherence and Matrix Metalloproteinases in Growth Patterns of Fungal Pathogens in Cornea

PURPOSE

To investigate the roles of adherence and matrix metalloproteinases (MMPs) in growth patterns of major fungal pathogens in cornea.

METHODS

Ninety-six eyes in 96 rabbits were equally divided into four groups receiving inoculation of fungal conidia of Aspergillus fumigatus, Candida albicans, Fusarium solani, and Penicillium citreo-viride, respectively, to induce fungal keratitis. Corneas in each group were obtained at 2, 8, 16 hr, and 1, 2, 3, 5, and 8 days after inoculation and were subjected to scanning electron microscopy, histopathological examination, and gelatin zymography. Eight saline-inoculated eyes in another eight rabbits served as controls.

RESULTS

All eyes in the fungus-inoculated groups developed fungal keratitis. The binding of conidia to corneal epithelial basement membrane was initiated earlier in the A. fumigatus and C. albicans groups than in the F. solani and P. citreo-viride groups. Destruction of basement membrane began at 1 to 3 days. Histopathologically, infiltration of inflammatory cells was more evident in the A. fumigatus and C. albicans groups than the F. solani and P. citreo-viride groups at 3 days. The hyphae of A. fumigatus and C. albicans traversed the cornea in a plane perpendicular to the stromal lamellae, whereas the hyphae of F. solani and P. citreo-viride lay parallel to the corneal lamellae. MMP-9 and MMP-2 were found in all infected corneas. At 3 days, proteolysis was most active; the level of MMP-9 was higher in the A. fumigatus and C. albicans groups than in the F. solani and P. citreo-viride groups. There were positive correlations among the number of binding conidia, degree of inflammation, and level of MMP-9 (p < 0.05).

CONCLUSIONS

The adherence ability, chemotaxis to neutrophils, and MMP-9 expression level differ in eyes with different fungal pathogens, which may contribute to the different growth patterns of fungi in cornea.

Epidemiologic aspects and clinical outcome of fungal keratitis in southeastern Brazil

PURPOSE

Fungal keratitis (FK) is a sight-threatening disease, more prevalent in developing regions. The present retrospective study was conducted in order to evaluate the epidemiologic and clinical aspects and the progression of FK in patients treated at two ophthalmologic reference centers in Southeast Brazil.

METHODS

The charts of patients with infectious keratitis treated between 2000 and 2004 were reviewed. For the 66 cases of FK confirmed by microbiological analysis, data related to patient, disease, and therapeutic approaches were obtained.

RESULTS

Mean patient age was 40.7+/-16 years. Fifty-three were men and 13 were women. Ocular trauma occurred in 40% of cases (27). Previous medications taken by the patients were quinolone in 72.5% and antimycotics in 30%. Visual acuity (VA) at presentation was >0.3 in 16% and <0.1 in 74.5%. Penetrant keratoplasty was performed in 38% and evisceration in 15%. The causing agents were Fusarium sp in 67%, Aspergillus sp in 10.5%, and Candida sp in 10%. Medication alone resolved 39% of cases within a mean period of 24.5+/-12 days. Final VA was >0.3 in 28%, and <0.1 in 63%.

CONCLUSIONS

Fungal keratitis presented as a disease with severe complications, predominantly among young males, and was mostly caused by filamentous fungi. The present information permits the establishment of preventive strategies. Reducing the time between onset and treatment and using more accessible specific medication would reverse the negative prognosis.

Expression of matrix metalloproteinases during experimental Candida albicans keratitis

PURPOSE

This study was designed to investigate the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) during the inception and progression of experimental keratomycosis.

METHODS

Scarified corneas of adult BALB/c mice were topically inoculated with Candida albicans strain SC5314 and monitored for disease severity. Infected and mock-infected corneas were compared at 1 day post inoculation (p.i.) with a murine gene microarray. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) determined MMP and TIMP levels at 1, 3, and 7 days p.i. for infected, mock-infected, and normal corneas. Immunostaining localized target proteins at 1 day p.i.

RESULTS

Eyes inoculated with C. albicans developed corneal infection with a mean clinical score of 8.2+/-0.8 at 1 day p.i. Compared to controls at 1 day p.i., MMP-8, -9, -10, -12, -13, -19, and TIMP-1 were significantly upregulated from fivefold to 375-fold by microarray and from threefold to 78-fold by real-time RT-PCR. Upregulated MMPs and TIMP-1 in the corneal epithelium and stroma of infected eyes correlated with the influx of acute inflammatory cells. Neither MMP-8 nor -13 expression was affected by mechanical trauma, but both increased >100-fold during the week after the onset of fungal keratitis. TIMP-1 expression rose from 21-fold more than controls at 1 day to 46-fold at 7 days p.i. by RT-PCR.

CONCLUSIONS

Transcriptional and translational levels of MMP-8, -9, -13, and TIMP-1 increase during the early stages of C. albicans keratitis, confirming findings for MMP-9 and TIMP-1 in other infectious keratitis models and suggesting roles for MMP-8 and -13.

Prospective comparison of microbial culture and polymerase chain reaction in the diagnosis of corneal ulcer

PURPOSE

To compare polymerase chain reaction (PCR) to microbial culture for the detection and identification of bacterial and fungal pathogens in microbial keratitis.

DESIGN

Prospective cohort study.

METHODS

A total of 108 consecutive corneal ulcers were cultured and analyzed by PCR using pan-bacterial and pan-fungal primers. PCR products were cloned, sequenced, and compared to culture results using standard bioinformatics tools.

RESULTS

Of the 108 samples, 56 were culture-positive, 25 for bacteria and 31 for fungi; 52 were culture-negative. After eliminating false-positive PCR products, 94 of 108 were positive by PCR, 37 for bacteria and 57 for fungi. Nineteen of 25 bacterial culture-positive samples were positive by PCR, and 29 of 31 samples culture-positive for fungi were positive by PCR. The majority of sequenced PCR products matched the positive culture results. Of the 52 culture-negative samples, 46 (88%) yielded pathogen deoxyribonucleic acid (DNA) PCR products, 18 bacterial and 28 fungal. These represented a variety of species, including at least three novel previously uncultured microbes.

CONCLUSIONS

PCR detects microbial DNA in the majority of bacterial and fungal corneal ulcers, and identifies potentially pathogenic organisms in a high proportion of culture-negative cases. Yield and concordance with culture are higher for fungal than bacterial ulcers. Practical use of the technique is limited by artefactual amplification of nonpathogenic organisms. PCR may be used as an adjunct to culture to identify potential pathogens in microbial keratitis.

Fungal keratitis in far north Queensland, Australia

BACKGROUND

Aboriginals and Torres Strait Islanders form a significant proportion of the population in far north Queensland and are at increased risk for many eye conditions. This study describes the pattern of fungal keratitis seen at Cairns Base Hospital, far north Queensland, Australia.

METHODS

A retrospective review of all cases of culture positive fungal keratitis presenting between 1998 and 2008. The records of 17 patients were reviewed for epidemiological, risk factor, microbiological, treatment and outcome data.

RESULTS

The study included 16 eyes from 16 patients. Five (31.25%) patients were of Aboriginal and Torres Strait Islander descent. Pre-disposing factors were ocular trauma (n = 7) and contact lens wear (n = 3). No patients were on topical steroids at presentation. All patients grew filamentous fungi with Fusarium the most common isolate (50%). Aspergillus, Curvularia and Lasiodiplodia theobromae were the next most common accounting for two cases each. Two patients developed corneal perforations, whereas two required penetrating keratoplasty and one required evisceration. Eight patients had a visual acuity of 6/18 or better at presentation and this increased to 13 patients at final follow up.

CONCLUSIONS

A significant proportion of the patients presenting to Cairns Base Hospital with fungal keratitis are Indigenous. The very high percentage of cases due to filamentous fungi is similar to other tropical regions of the world. The very low rates of Candida infection and steroid use prior to presentation are in contrast to studies from temperate areas such as Melbourne and Philadelphia.

Fungal keratitis in the United Kingdom 2003-2005

PURPOSE

To describe the incidence and current management of fungal keratitis in the United Kingdom.

METHODS

Cases were identified prospectively through the British Ophthalmologic Surveillance Unit (BOSU) from December 2003 to November 2005. Questionnaire data were requested at diagnosis and at 6 months follow-up. Inclusion criteria were a positive culture or microsopic proof from a scraping or biopsy, and a normal residence in the United Kingdom.

RESULTS

Data were available on 39 confirmed cases at diagnosis and 34 cases at follow-up. The minimum average annualised incidence was 0.32 (95% CI, 0.24-0.44) cases per million individuals. In 22 cases (56%), only Candida was isolated and 14 of these (63%) had prior ocular surface disease treated with topical steroid. A filamentary fungus infection was more common in male patients (P=0.02), often following trauma, and the differences in risk factors between types of fungal infection was statistically significant (P<0.001). One case had a mixed yeast and filamentary fungus infection. The most frequent initial topical therapies were amphotericin B (38%) or econazole (28%). In addition, oral fluconazole was used in 11 (31%) patients and oral itraconazole in six (15%). At follow-up, the vision in 15 eyes (44%) was <6/60 including three eyes eviscerated.

CONCLUSIONS

This study provides data on the minimum incidence of fungal keratitis in the United Kingdom. It provides evidence of frequent delay in diagnosis after presentation to eye departments, inconsistent management, and poor outcome. Issues that can now be addressed.

Antifungal susceptibility for common pathogens of fungal keratitis in Shandong Province, China

PURPOSE

To analyze common pathogens of fungal keratitis and results of antifungal drug sensitivity test in Shandong Province, China and provide guidance for appropriate choice of antifungal drugs in clinic.

DESIGN

Retrospective, noncomparative study.

METHODS

The pathogens isolated from 674 fungal keratitis patients between January 1, 2001 and December 31, 2006 were cultured and identified in Shandong Eye Institute, of which some common strains were tested for sensitivity to antifungal drugs.

RESULTS

Fungi were positively cultured in 549 (81.5%) patients, in which the dominating pathogen was genus Fusarium (77.6%), with F. solani (37.3%), F. moniliforme (30.0%), and F. oxysporum (27.9%) being common species; Fusarium was mostly sensitive to natamycin, next to amphotericin B, and then to terbinafin. The second common pathogen was genus Aspergillus (10.8%), in which the main species were A. flavus (49.2%) and A. fumigatus (35.6%); Aspergillus was mostly sensitive to natamycin, next to terbinafin, and then to amphotericin B. Relatively, both Fusarium and Aspergillus were insensitive to ketoconazole, miconazole, itraconazole, fluconazole, and fluorocytosine.

CONCLUSIONS

Fusarium is the most common pathogen of fungal keratitis, followed by Aspergillus, in Shandong Province, China. Natamycin is still the first choice in the treatment of hyphomycetic keratitis. Fusarium and Aspergillus are also sensitive to amphotericin B and terbinafin. Early diagnosis and treatments are vital to good prognosis in the treatment of fungal keratitis.

MyD88 regulation of Fusarium keratitis is dependent on TLR4 and IL-1R1 but not TLR2

The fungal pathogens Fusarium solani and Fusarium oxysporum cause severe corneal disease in the United States and worldwide and were the causative organisms in a recent outbreak of contact lens-associated keratitis. To characterize innate immunity in Fusarium keratitis, we developed a murine model in which conidia are injected into the corneal stroma. Immunocompetent C57BL/6 mice rapidly developed severe corneal opacification associated with neutrophil infiltration and clearance of Fusarium hyphae. In contrast, neutrophil infiltration was delayed in MyD88-/- mice, resulting in uncontrolled growth of Fusarium hyphae in the corneal stroma and anterior chamber, and eventually resulting in corneal perforation. Corneal opacification scores in TLR2-/-, TLR4-/-, and TLR2/4-/- mice were similar to those of C57BL/6 mice; however, TLR4-/- and TLR2/4-/- mice had impaired antifungal responses. The phenotype of infected IL-1R1-/- mice was similar to that of MyD88-/- mice, with uncontrolled fungal growth resulting in corneal perforation. IL-1R1-/- mice also produced significantly less CXCL1/KC in the corneal stroma compared with C57BL/6 mice consistent with delayed neutrophil recruitment to the corneal stroma. Together, these findings indicate that IL-1R1 and MyD88 regulate CXC chemokine production and neutrophil recruitment to the cornea, and that TLR4 has an important role in controlling growth and replication of these pathogenic fungi.

Keratitis in children as seen in a tertiary hospital in Africa

BACKGROUND

Blindness studies have shown that keratitis complicated by the use of traditional eye medications is a major factor of childhood blindness in developing countries. Most cases of such keratitis were presumably due to nutritional causes or bacterial infection. The patterns of outcome that are seen in hospitals may be different.

OBJECTIVE

To determine the clinical types of keratitis seen in children at a tertiary hospital and compare with other reports.

METHOD

A retrospective analysis was conducted using the records of children who presented with keratitis to the eye unit of the University College Hospital, Ibadan, Nigeria, over a three-year period from January 2003 to December 2005. Information obtained were the demographic data, the etiological type of keratitis and visual outcome of management.

RESULT

Ninety-five patients with keratitis seen during this three-year period were children. Of these, 47 (49.5%) patients had presumed herpes simplex keratitis; 78.9% of children with herpes simplex keratitis presented with combined epithelial and stromal disease; 21 (22.1%) had keratitis that was associated with a recent measles infection and protein calorie malnutrition. Fifteen (15.8%) had keratitis associated with phlyctenular keratoconjunctivitis, eight (8.4%) patients had bacterial/fungal keratitis, while four (4.2%) had vernal ulcers. Both the right and left eyes were affected in 47.6% and 52.4% of cases, respectively. Bilateral keratitis occurred in eight of the children with measles, and six patients with herpes simplex keratitis. Fifty-nine eyes had visual acuity recorded after the keratitis healed. Of these, the visual outcome was very poor in six (20.0%) eyes with herpes simplex keratitis and eight (100%) eyes with bacterial/fungal keratitis. All eyes with suppurative keratitis associated with measles developed dense corneal scars or were perforated.

CONCLUSION

Herpes simplex keratitis was the leading cause of keratitis in children seen at this tertiary hospital, and clinical presentations do not differ from those reported in other populations. Very poor visual outcome was associated with all types of keratitis except those with herpes keratitis. Blindness studies may underrepresent the burden of herpes simplex keratitis in the location of this study.

Use of chlorazol black E mounts of corneal scrapes for diagnosis of filamentous fungal keratitis

PURPOSE

To determine whether chlorazol black E, a chitin-specific stain, can be used to detect fungal filaments in corneal scrapings and to compare its sensitivity as a diagnostic aid for fungal keratitis with that of gram and lactophenol cotton blue stains.

DESIGN

Prospective study, laboratory investigation.

METHODS

Between December 1, 2005 and July 31, 2006, corneal scrapes from 163 patients with ulcerative keratitis were used for culture and to prepare smears that were stained by lactophenol cotton blue, chlorazol black E, or gram stains. A diagnosis of fungal keratitis was established if fungal growth occurred on the inoculated areas of multiple culture plates.

RESULTS

Fungi were isolated from corneal scrapes of 82 patients. Taking fungal culture positivity as the gold standard for diagnosis of fungal keratitis, direct microscopic examination of chlorazol black E mounts had a sensitivity of 82% and specificity of 98%; culture results and chlorazol black E results were identical in 89.6% of patients. Lactophenol cotton blue mounts and gram-stained smears had a sensitivity of 85%, specificity of 90% to 91%, and 88% agreement with culture results.

CONCLUSIONS

Chlorazol black E can be used for detection of fungal filaments in corneal scrapings; however, it is less sensitive than lactophenol cotton blue and gram stains as a diagnostic aid for fungal keratitis.

Predisposing factors and etiologic diagnosis of ulcerative keratitis

PURPOSE

To determine the predisposing factors, demographic characteristics, and etiology of ulcerative keratitis in a referral center in Bangkok, Thailand.

METHODS

The medical records of admitted patients with positive-culture ulcerative keratitis were retrospectively reviewed for demographic data, predisposing factors, and microbial culture results. Predisposing factors were compared between bacterial and fungal keratitis.

RESULTS

From January 2001 to December 2004, there were 127 positive-culture ulcerative keratitis cases. The most frequent microbiological diagnosis was bacterial keratitis (76 eyes, 60%), followed by fungal (48 eyes, 38%) and Acanthamoeba keratitis (3 eyes, 2%). The most common organisms isolated were Pseudomonas spp. for bacteria and Fusarium spp. for fungus. Compared with bacterial keratitis, fungal keratitis was more likely to be associated with ocular trauma (odds ratio = 11.20; 95% confidence interval, 3.62-34.66) but less likely to be associated with contact lens wear (odds ratio = 0.02; 95% confidence interval, 0.01-0.08).

CONCLUSIONS

In our study, Pseudomonas and Fusarium species are the most common causes of bacterial and fungal keratitis, respectively. Fungal keratitis was more likely than bacterial keratitis to be associated with ocular trauma, whereas fungal keratitis was less likely to be associated with contact lens wear.

Specific detection of fungal pathogens by 18S rRNA gene PCR in microbial keratitis

Background

The sensitivity and specificity of 18S rRNA polymerase chain reaction (PCR) in the detection of fungal aetiology of microbial keratitis was determined in thirty patients with clinical diagnosis of microbial keratitis.

Methods

Corneal scrapings from patients were used for Gram stain, culture and PCR analysis. PCR was performed with primer pairs targeted to the 18S rRNA gene. The result of the PCR was compared with conventional culture and Gram staining method. The PCR positive samples were identified by DNA sequencing of the internal transcribed spacer (ITS) region of the rRNA gene. Main outcome measures were sensitivity and specificity of PCR in the detection of fungus in corneal keratitis.

Results

Combination of microscopy and culture gave a positive result in 11 of 30 samples of microbial keratitis. PCR detected 10 of 11 samples that were positive by conventional method. One of the 19 samples that was negative by conventional method was positive by PCR. Statistical analysis revealed that the PCR to have a sensitivity of 90.9% and specificity of 94.7% in the detection of a fungal aetiology in microbial keratitis.

Conclusion

PCR is a rapid, sensitive and useful method to detect fungal aetiology in microbial keratitis.

Antifungal efficacy of voriconazole, itraconazole and amphotericin b in experimental fusarium solani keratitis

PURPOSE

To evaluate the efficacy of topical voriconazole in an experimental rabbit model of Fusarium keratitis.

METHODS

Fungal keratitis was induced in the right eyes of 24 New Zealand rabbits. 8.6 x 10(3) CFU/0.1 ml F.solani spore suspension was injected midstromally into the central cornea. Group 1 received topical amphotericin B 0.15%, group 2 received topical itraconazole 1% and group 3 received topical voriconazole 1% hourly between 08:00 to 22:00 on days 1 and 2; 4 times daily on days 3-5. Control group received topical balanced salt solution at identical intervals. The eyes were examined clinically with a scoring system before treatment (day 0), on day 3 and on day 5. Cultures were taken from the lesion by scraping at the end of the treatment. Clinical scores and microbiologic results were analyzed statistically.

RESULTS

In the control group, keratitis progressed clinically and colony level was 2 x 10(3) CFU at day 5. In all treatment groups, progression of keratitis was inhibited clinically. Culture was sterile in the group receiving amphotericin B. Colony level was 0.3 x 10(2) CFU in the itraconazole group and 2 x 10(2) CFU in the voriconazole group at day 5.

CONCLUSION

Progression of keratitis was inhibited clinically in all treatment groups. Colony level decreased significantly in all treatment groups. As a result, itraconazole 1% and voriconazole 1% were found to be effective in Fusarium keratitis clinically and microbiologically, although their activity was not as effective as amphotericin B 0.15%.

Fungal keratitis in London: microbiological and clinical evaluation

PURPOSE

To review cases of culture-positive fungal keratitis seen at Moorfields Eye Hospital over a 13-year period to January 2007.

METHODS

Isolates were identified retrospectively from laboratory reports. The clinical records were reviewed. The fungal type, risk factors for infection, in vitro sensitivity, and clinical outcome were recorded.

RESULTS

There were 66 isolates from 65 patients (men, 53.8%). Forty (60.6%) of the isolates were subspecies of Candida. The average interval from the onset of keratitis to confirmation of fungal infection was 3.4 weeks (median, 1.0 week; range, 0-16 weeks). Prior ocular surface disease (OSD) or a penetrating keratoplasty (PK) was present in 38 (97.4%) patients with Candida infection, and 29 (74.4%) patients with Candida infection were using topical steroid at the time of diagnosis. The principal risk factors for filamentary fungal infection were trauma (8 cases, 30.8%) or cosmetic contact lens wear (8 cases, 30.8%), with OSD or a prior PK each present in 5 (19.2%) cases. The difference in the proportions of risk factors between the 2 fungal groups was statistically significant (P < 0.000). The visual outcome was similar between groups, and at final review, 27 (41.5%) eyes had a visual acuity of < or = 1/60 and 3 (4.6%) eyes were eviscerated. In vitro sensitivity testing showed full or part sensitivity in 100% of 55 isolates tested against econazole, 87.9% of 58 isolates tested against amphotericin, 75% of 40 isolates tested against itraconazole, and 100% of 20 isolates tested against voriconazole.

CONCLUSIONS

Candida was the principal isolate, usually from eyes with OSD or a prior PK treated with topical steroids.

Keshav BR, Zacheria G, Ideculla T, Bhat V, Joseph M.. Epidemiological characteristics of corneal ulcers in South sharqiya region

OBJECTIVES

To understand the epidemiology, predisposing factors, etiology and the outcome of management of corneal ulcers in South Sharqiya Region of Oman.

METHODS

188 patients who presented to us in eye Ophthalmology Department of Sur regional hospital with corneal ulcers were analyzed retrospectively. The historical aspects including the systemic and local predisposing factors, clinical picture of the ulcer which was noted on slit lamp at the time of presentation, results of culture for which material was taken by scraping of the ulcer, and its sensitivity pattern, type of management, and its outcome, were noted and the results were interpreted.

RESULTS

60.83% were males above the age of 60 years. Severe ulcers were seen in 36.17% of cases. 43.18% of cases showed positive culture of which 88.2% were bacteria and rest were fungal isolates. Of the bacteria 53.84% were pseudomonas, and 20% staphylococcus. 83.5% were put on fortified gentamycin and 68.61% were on cefuroxime in the initial dual therapy. 37.23% were on ciprofloxacin one time or another during the course of the ulcer. 69.14% of cases recovered fully and 9.57% improved. 54.25% needed hospitalization for less than 1 week and 34% for less than 2 weeks. 58.76% of cases recovered in less than 3 weeks. As local predisposing factors 45 cases (24%) were post surgery, and 29 cases (15.4%) were having CDK (climatic droplet keratopathy). Diabetes was seen in 8.5% of cases.

CONCLUSION

Corneal ulcer was seen predominantly in males above the age of 60 years, pseudomonas being the main etiological organism. Dual therapy was the commonest empirical therapy. No major systemic risk factor was identified. Post surgical and CDK were the predominant local risk factors.

Treatment Failure after Lamellar Keratoplasty for Fungal Keratitis

PURPOSE

To evaluate treatment failure after lamellar keratoplasty (LK) for fungal keratitis.

DESIGN

Retrospective, interventional case series.

PARTICIPANTS

Two hundred eighteen patients (218 eyes) with fungal keratitis who failed to respond to medical therapy and underwent LK at the Shandong Eye Institute between January 1998 and July 2005.

METHODS

Detailed medical history was obtained from each patient. Antifungal drugs were administered for at least 7 days before LK was performed. A trephine that was 0.5 mm larger in diameter than the fungal infection was used to create a lamellar incision to excise the ulcer. After treatment failure was observed after surgery, penetrating keratoplasty (PK) was performed. The distribution of risk factors for treatment failure was analyzed.

MAIN OUTCOME MEASURES

Clinical features and risk factors for treatment failure.

RESULTS

Seventeen patients (7.8%) experienced treatment failure within 2 weeks after LK, including 15 patients within 1 week. All cases of treatment failure displayed increasing local irritation and hyphal infiltration in the recipient LK bed and subsequently were cured by PK. A higher rate of inadequate treatment with LK was found in the cases with Aspergillus species, in those to whom glucocorticoids or immunosuppressants were administered, and in those with hypopyon or endothelial plaque before LK.

CONCLUSIONS

Treatment failure after LK for fungal keratitis can be reduced significantly with adept intraoperative skills. Aspergillus species, use of glucocorticoids or immunosuppressants, and presence of hypopyon or endothelial plaque before LK should be noted as major risk factors. Prompt recognition and management of failed LK with PK can achieve successful outcomes.

In vitro susceptibility patterns of fungi associated with keratomycosis in horses of the northeastern United States: 68 cases (1987-2006)

OBJECTIVE

To determine in vitro susceptibility patterns of fungi associated with keratomycosis in horses in the northeastern United States and compare those patterns with results of studies from other geographic regions.

DESIGN

Retrospective case series.

ANIMALS

68 horses with keratomycosis.

PROCEDURES

Medical records of horses with a clinical diagnosis of keratomycosis, positive results of corneal fungal cultures, and susceptibility data were reviewed from the years 1987 to 2006. Fungal identification and in vitro antifungal susceptibility test results were recorded. The percentage of susceptible isolates was compared among antifungals for all isolates together and for the most common genera individually.

RESULTS

74 fungal isolates from 68 horses that met inclusion criteria were identified. Aspergillus, Candida, and Fusarium spp were the most frequent isolates. Grouped isolates had the highest percentage of susceptibility to nystatin (87.7%), natamycin (87.5%), and clotrimazole (80.6%). Grouped isolates had the lowest percentage of susceptibility to fluconazole (15.8%) and miconazole (27.5%). Aspergillus spp (> or = 81.0%) were most susceptible to nystatin, clotrimazole, itraconazole, and natamycin. Candida spp (100%) were most susceptible to ketaconazole, natamycin, and nystatin. Fusarium spp (100%) were only consistently susceptible to natamycin.

CONCLUSIONS AND CLINICAL RELEVANCE

On the basis of in vitro susceptibility testing, nystatin, natamycin, or clotrimazole is recommended for initial topical treatment of keratomycosis in horses from the northeastern United States. Contrary to results of studies of ocular fungal isolates of horses from other regions, Candida spp were identified more frequently and miconazole had lower in vitro efficacy in the present study.

Relationship between climate, disease severity, and causative organism for contact lens-associated microbial keratitis in Australia

PURPOSE

To evaluate associations between disease severity, causative organism, and climatic variation in contact lens-related microbial keratitis in Australia.

DESIGN

Prospective, observational case series.

METHODS

Contact lens wearing patients (n = 236) with presumed microbial keratitis presenting to private and hospital ophthalmologists in Australia between October 1, 2003 and September 30, 2004 were identified prospectively. Clinical details, management information, and microbiology data were collected and cases were graded for severity based on lesion size and location criteria. Causative organisms were assigned to "environmental" or "endogenous" groups. Climate zone and daytime temperature and humidity were determined for the geographic location of each event. The main outcome measures were disease severity, causative organism, and climate zone.

RESULTS

Severe contact lens-related microbial keratitis was more likely to occur in warmer, humid regions of the country (P < .001), compared with smaller, increasingly peripheral corneal lesions that were more common in cooler conditions (P < .001). Culture-proven keratitis was predominantly caused by environmental organisms with Pseudomonas aeruginosa being recovered most frequently. Environmental organisms were isolated more commonly from tropical regions of the country and also accounted for nearly all cases of vision loss that occurred during the study period. Humidity did not have a significant effect on causative organism.

CONCLUSIONS

Climatic conditions play a role in disease severity and causative organism in contact lens-related microbial keratitis and therefore have implications for practitioners involved in contact lens care and contact lens wearers who live in or travel to the tropics.

Causes of childhood visual impairment and unmet low-vision care in blind school students in Ghana

The purpose of this study was to determine the causes of childhood visual impairment and blindness in students of a school for blind children, to determine how many students had some residual vision, and to evaluate any unmet low-vision care. A survey of students in the blind school was conducted in two parts in May-June and then October 2003. The sample consisted of 201 students who became blind before the age of 16. Information was obtained from student interviews, doctors' referral notes and ophthalmic examination of all students who consented. Students with residual vision had low-vision assessments. These investigations were supplemented with active participation of the investigators in Parent-Teacher Association meetings and focus group discussions with parents. One hundred and ninety-nine students consented and were recruited, whereas two declined. Ninety-six became visually impaired within their first year of life and 33 by the age of 5 years. Pathology of the cornea and then the lens were the commonest causes of blindness. One hundred and eight students were totally blind, whereas 87 (43.7%) had some residual vision and formed the target for the second part of the study. Fifty-one out of 77 of this target group who turned up for low-vision examination had useful residual vision by the World Health Organisation (WHO) low-vision examination chart. Spectacle magnifiers aided two students to read normal print at N5 and N8, respectively. Different visual aids would help enhance the residual vision in some of the others. Emotional trauma was apparent in parents and teachers. Children who became blind later in life remained in shock for a longer time and adapted less well to their visual impairment. Visual impairment in the population is not uncommon. Some causes are preventable. There is a significant unmet need for low-vision care, particularly amongst children in Ghana, and perhaps many countries in the West Africa subregion. It is hoped that the findings from this study will help spur sustained interventions.

Evaluation of polymerase chain reaction-based ribosomal DNA sequencing technique for the diagnosis of mycotic keratitis

PURPOSE

To evaluate the polymerase chain reaction (PCR) and sequencing-based ribosomal deoxyribonucleic acid (rDNA) typing technique for rapid and sensitive diagnosis of fungal keratitis.

DESIGN

Laboratory investigation.

METHODS

The present study included culture-based methods along with PCR and ITS2/5.8S rDNA sequencing to evaluate fungal infections in 32 corneal scrapings from patients with suspected mycotic keratitis.

RESULTS

Good correlation was found between the culture and PCR rDNA sequencing-based methods. We also identified fungal strains that were noncultivable in routine culture medium and fungal strains, which have been reported scarcely in previous reports from eastern Indian studies.

CONCLUSIONS

The PCR and rDNA sequencing-based approaches may be useful alternatives to culture-based techniques for the rapid and sensitive diagnosis of fungal keratitis. We found that clinically significant pathogenic fungal strains can be detected and differentiated by this method in a short period. This method therefore is useful for the early treatment of fungal infection.

Inflammatory response to fungal keratitis

Ocular fungal infections occur worldwide and are important contributors to vision loss. While many aspects of the microbe and host interaction involved in fungal keratitis remain undefined, two aspects known to affect susceptibility are disruption of the epithelial barrier and immunosuppression of the host. Our recent pathogenesis studies using an experimental murine model have provided insight into the influence of these factors on keratomycosis. Increased susceptibility was associated with greater neutrophilic infiltration, greater fungal invasion of the corneal stroma, up-regulation of matrix metalloproteinase-9, and morphogenic switching from yeast to hyphae. Understanding the pathogenic events of fungal keratitis will identify potential targets for therapeutic intervention of these sight-threatening infections.

Initial therapy for suppurative microbial keratitis in Iraq

OBJECTIVE

To provide data-based guidelines for selection of an appropriate initial therapy for management suppurative microbial keratitis (SMK) in Iraq.

METHODS

This case-series study enrolled patients with clinical signs of suppurative keratitis suspected of being microbial, presented prospectively at Ibn Al-Haetham Teaching Eye Hospital from April 2002 to March 2005. Predisposing factors, microbial profile and sensitivities of isolated bacteria were determined. If direct microscopic examination of smears was negative for fungal elements, initial therapy started with ciprofloxacin 0.3% eye-drops. Subsequent treatment depends on clinical response and cultures' results.

RESULTS

Out of 396 cases enrolled, positive cultures were obtained in 232 cases (58.6%). The predominating agents isolated were Gram-positive cocci (Staphylococcus and Streptococcus) 75 cases (18.9%); Pseudomonas 68 cases (17.2%); and fungal species 74 cases (18.7%). Treatment was initiated with ciprofloxacin eye-drops in 364 cases, a favourable response was recorded in 185 cases (50.8%), addition of other antimicrobial drugs was required in 56 cases (15.4%), while failure of treatment was recorded in 123 cases (33.8%).

CONCLUSION

Use of ciprofloxacin eye drops alone as an initial therapy cannot cover most of the causative agents of SMK in Iraq. Addition of another drug can provide a better coverage for the predominating causative agents. The choice of this additional drug is based on the suspected infecting agent depending on the regional predisposing factors, and the clinical features.

Infectious keratitis

PURPOSE OF REVIEW

Infectious keratitis is a medical emergency. Improper management can lead to marked loss of vision. This review identifies recent trends in the study of infectious keratitis.

RECENT FINDINGS

A multicountry outbreak of Fusarium keratitis emphasizes that contact lens wear is a major risk factor for infectious keratitis. Acanthamoeba and fungal keratitis are the most expensive forms of infectious keratitis to treat. Noninvasive methods and molecular techniques have improved diagnosis of infectious keratitis. Fortified topical antibiotics and fluoroquinolones are still the mainstay of bacterial keratitis therapy. Voriconazole and new routes of administration of conventional antifungals appear promising for fungal keratitis. Antivirals and amelioration of host inflammatory response are promising for viral keratitis; the host response is also crucial in pathogenesis of Pseudomonas aeruginosa keratitis. Trauma-induced bacterial and fungal keratitis and contact lens-associated keratitis are preventable entities.

SUMMARY

Improved modalities of diagnosis and treatment have improved the outcome of infectious keratitis, but therapy of acanthamoebal, fungal and P. aeruginosa keratitis is still a challenge. Effective strategies must neutralize potential risk factors and counter host response overactivity without impairing killing of infecting microorganisms. Trauma-induced bacterial and fungal keratitis can be prevented.

Clinical characteristics and outcome of Candida keratitis

PURPOSE

To characterize the clinical features and therapeutic outcome of Candida keratitis.

DESIGN

Retrospective, observational case series.

METHODS

We reviewed 26 patients treated for Candida keratitis, including two with recurrent keratitis and one with bilateral infection.

RESULTS

Of 29 keratitis episodes resulting from Candida albicans (n = 20) or Candida parapsilosis (n = 9), 16 (55%) complicated chronic ocular surface disease, and nine (31%) followed previous keratoplasty. Only two were clinically suspected to have keratomycosis at initial presentation, and 21 (72%) used antibacterial therapy before corneal scrapings. Reconstructive keratoplasty occurred more often in previously grafted eyes (P = .03). Visual outcome was 20/60 or better in six (100%) medically treated eyes with good presenting visual acuity but in only five eyes (24%) with worse initial vision (P = .002).

CONCLUSIONS

Candida keratitis is an opportunistic infection of a compromised cornea that often is misdiagnosed initially and, despite antifungal therapy, occasionally requires corneal grafting.

Expression of Matrix Metalloproteinases 2 and 9 in Experimental Corneal Injury and Fungal Keratitis

PURPOSE

Levels of matrix metalloproteinases (MMPs) can be modulated during corneal infection, but little is known about MMP profiles during fungal keratitis. The purpose of this study was to determine the effect of corneal trauma and immunosuppressive treatment on the expression kinetics of MMP-2 and MMP-9 during experimental keratomycosis.

METHODS

Corneas of immunocompetent and cyclophosphamide-treated adult BALB/c mice were topically inoculated with 1 x 10 culturable units of Fusarium solani or mock-inoculated with or without superficial corneal scarification. Eyes were scored daily for disease severity and processed for zymography after 1.5 hours, 6 hours, 1 day, 4 days, or 8 days. Gelatinase activity was densitometrically quantitated and normalized to MMP-2 and MMP-9 controls.

RESULTS

MMP-9 levels in nontraumatized eyes transiently increased at 6 hours after fungal exposure, but this increase was inhibited by cyclophosphamide treatment. Corneal injury significantly induced early MMP-9 expression that returned to baseline levels within 4 days. Cyclophosphamide pretreatment reduced and delayed MMP-9 after scarification. Fusarium exposure dampened the MMP-9 response to corneal trauma in immunocompetent and cyclophosphamide-treated animals. Ocular levels of MMP-2 were not affected by scarification, fungal exposure, or immunosuppressive treatment.

CONCLUSIONS

Ocular MMP-9 levels, but not MMP-2 levels, increased soon after corneal injury. A similar, although muted, MMP-9 response occurs during early filamentous fungal keratitis, with a kinetic profile similar to corneal disease progression. The early stage of ulcerative keratitis may involve selective regulation of corneal matrix metalloproteinases, suggesting an initial opportunity for therapeutic intervention.

Microbial keratitis in South India: influence of risk factors, climate, and geographical variation

PURPOSE

To determine the influence of risk factors, climate, and geographical variation on the microbial keratitis in South India.

METHODS

A retrospective analysis of all clinically diagnosed infective keratitis presenting between September 1999 and August 2002 was performed. A standardised form was filled out for each patient, documenting sociodemographic features and information pertaining to risk factors. Corneal scrapes were collected and subjected to culture and microscopy.

RESULTS

A total of 3,183 consecutive patients with infective keratitis were evaluated, of which 1,043 (32.77%) were found to be of bacterial aetiology, 1,095 (34.4%) were fungal, 33 (1.04%) were Acanthamoeba, 76 (2.39%) were both fungal and bacterial, and the remaining 936 (29.41%) were found to be culture negative. The predominant bacterial and fungal pathogens isolated were Streptococcus pneumoniae (35.95%) and Fusarium spp. (41.92%), respectively. Most of the patients (66.84%) with fungal keratitis were between 21 and 50 years old, and 60.21% of the patients with bacterial keratitis were older than 50 (p < 0.0001) (95% CI: 5.19-7.19). A majority of patients (64.75%) with fungal keratitis were agricultural workers (p < 0.0001) [odds ratio (OR): 1.4; 95% CI: 1.19-1.61], whereas bacterial keratitis occurred more commonly (57.62%) in nonagricultural workers (p < 0.0001) (OR: 2.88; 95% CI: 2.47-3.36). Corneal injury was identified in 2,256 (70.88%) patients, and it accounted for 92.15% in fungal keratitis (p < 0.0001) (OR: 7.7; 95% CI: 6.12-9.85) and 100% in Acanthamoeba keratitis. Injuries due to vegetative matter (61.28%) were identified as a significant cause for fungal keratitis (p < 0.0001) (OR: 23.6; 95% CI: 19.07-29.3) and due to mud (84.85%) for Acanthamoeba keratitis (p < 0.0001) (OR: 26.01; 95% CI: 3.3-6.7). Coexisting ocular diseases predisposing to bacterial keratitis accounted for 68.17% (p < 0.0001) (OR: 33.99; 95% CI: 27.37-42.21). The incidence of fungal keratitis was higher between June and September, and bacterial keratitis was less during this period.

CONCLUSION

The risk of agricultural predominance and vegetative corneal injury in fungal keratitis and associated ocular diseases in bacterial keratitis increase susceptibility to corneal infection. A hot, windy climate makes fungal keratitis more frequent in tropical zones, whereas bacterial keratitis is independent of seasonal variation and frequent in temperate zones. Microbial pathogens show geographical variation in their prevalence. Thus, the spectrum of microbial keratitis varies with geographical location influenced by the local climate and occupational risk factors.

Fungal keratitis in Melbourne

BACKGROUND

Description of the clinical and microbiological spectrum of fungal keratitis at a tertiary eye care hospital in Melbourne, Australia.

METHODS

Retrospective review of all patients with keratitis with positive fungal cultures from corneal or associated samples presenting to the Royal Victorian Eye and Ear Hospital, Melbourne, Australia from July 1996 to May 2004. Demographic data, predisposing factors, features on presentation, management, outcomes and microbiological data were collected and analysed.

RESULTS

The study included 56 eyes of 56 patients. Thirty-five patients were treated as 'typical' fungal keratitis and used for description and analysis, with a mean follow up of 18 months. Ocular trauma (37.1%), chronic steroid use (31.4%) and poor ocular surface (25.7%) were the major predisposing factors. Perforation was seen in 25.7% of patients, penetrating keratoplasty was required in 9 (25.7%) patients and evisceration was performed in 2 (5.7%) patients. Candida albicans (13 patients, 37.2%) was the most common fungal isolate accounting for more than one-third of all organisms followed by Aspergillus fumigatus (six patients, 17.1%) and Fusarium sp. (five patients, 14.3%).

CONCLUSIONS

The present study describes the clinical patterns of fungal keratitis in Melbourne, Australia and contrasts them with reports from other areas of the world. A high incidence of C. albicans infection and the prior use of steroids in high proportion of the patients are highlighted in this study.

Therapeutic keratoplasty for advanced suppurative keratitis

PURPOSE

To determine indications, therapeutic success, and corneal transplantation techniques for advanced medically uncontrolled infectious keratitis.

DESIGN

Retrospective, interventional case series.

METHODS

A review of 92 consecutive patients (1991 to 2002) who underwent therapeutic keratoplasty for acute infectious keratitis performed at Singapore National Eye Centre. Causative organism(s) were identified and outcomes were evaluated in terms of infectious cure (therapeutic success), graft clarity, and visual acuity.

RESULTS

Pseudomonas aeruginosa (58.7%) and Fusarium species (32.3%) were the predominant organisms for bacterial and fungal keratitis, respectively. Keratoplasty types included penetrating keratoplasty (PK; n = 80) and lamellar keratoplasty (n = 12). Mean graft diameter was 9.5 mm (range, 5.5 to 14 mm). Seventy-four patients (80.4%) achieved therapeutic success after one keratoplasty procedure, three patients were cured after a second keratoplasty. Life-table survival analysis computed the one-year therapeutic survival for bacterial and fungal keratitis as 76.6% and 72.4%, respectively (P = .76). The Kaplan-Meier one-year survival rate for PK optical clarity was 72%. Twenty-two patients underwent repeat keratoplasty for various reasons (optical, n = 8; recurrent primary infection, n = 7; perforation or subsequent new infections, n = 7). Of the 15 patients for whom therapy failed, 11 had fungal keratitis. Infection recurrence time was four days to one year. Most recurrences (n = 11) appeared within six weeks after surgery.

CONCLUSIONS

Therapeutic keratoplasty may treat severe, refractory infectious keratitis effectively. High cure rates are achievable, although infection recurrence despite prolonged treatment remains a significant problem in fungal keratitis.

Microbial keratitis in West Anatolia, Turkey: a retrospective review

PURPOSE

To analyze the clinical and microbiological characteristics of microbial keratitis in West Anatolia, Turkey during a 16-year period.

METHODS

This is a retrospective study in which medical records were reviewed for all eyes with clinically diagnosed microbial keratitis presenting at the Izmir Ataturk Training and Research Hospital from January 1990 to December 2005. Risk factors, microbial isolations and clinical features were analyzed.

RESULTS

Microbial keratitis was diagnosed for 620 eyes in 620 patients (250 women and 370 men; mean age: 54.13 years +/- 20.06). Pathogens from cultures were identified for 225 eyes (36.2%) and included Gram-negative (8.9%) and Gram-positive micro-organisms (68.8%) and fungi (22.3%). Staphylococcus epidermidis was the most commonly isolated micro-organism (26.6%), followed by S. aureus (24.4%), Streptococci pneumoniae (15.5%), fungi (22.3%), Pseudomonas species (6.6%), Enterobacter (2.2%) and Corynebacterium (2.2%). Ocular trauma was the most common predisposing factor (26.6%). Mean duration from onset of symptoms to diagnosis was 11.68 +/- 11.29 days.

CONCLUSION

Staphylococci are the most commonly isolated microbial agents in cases of infectious keratitis in West Anatolia, Turkey. These findings will provide valuable background information and facilitate successful treatment in this region, and they will be useful as reference data for the particular population in this region as a basis for empirical antibiotic therapy.

Nocardia Keratitis

PURPOSE

To correlate the clinical presentation and treatment outcome of Nocardia keratitis with the time to diagnosis, different species and with the drug sensitivity pattern.

METHOD

Patients with Nocardia corneal ulcers were studied at a tertiary eye care center. Speciation of Nocardia isolates was done by sequencing the 16s rRNA gene. Clinical response to treatment was assessed by chart review.

RESULTS

Twenty one (65.3%) patients presented within 15 days of the onset of symptoms with typical clinical features of Nocardia keratitis, ie, a ring-like distribution of superficial infiltrates in a wreath pattern. Eight patients (25%) who presented after 15 days and within 30 days had an ulcer resembling fungal keratitis. N. Cyriacigeorgica (n = 11; 34.37%), N. asteroides (n = 9; 28%), N. farcinica (n = 7; 22%,) and N. Otitidiscaviarum (n = 5; 16%). All the species had 100% sensitivity to amikacin, sulphamethoxazole, imipenem and co-trimoxazole. Time to diagnosis of the infection was significantly associated with the different types of clinical presentation; those presenting early having the typical clinical picture (P = 0.004). Patients (73%) presenting within 15 days showed a highest recovery rate. (P = 0.045). The recovery time of the patients when compared with species showed those who were infected with N. cyriageorgica had a healing time of less than 15 days. Clinically, healing was faster when treated with 2% amikacin. Visual outcome improved in fourteen patients (44%) and sixteen (50%) patients remained the same (P = 0.0001).

CONCLUSION

Characteristic clinical picture of Nocardia is dependant on early presentation. It could be mistaken for fungal keratitis. Microbiological confirmation is important. Drug of choice for Nocardia keratitis is amikacin.

Comparison of Micafungin and Fluconazole for Experimental Candida Keratitis in Rabbits

PURPOSE

To evaluate the efficacy of subconjunctival injection of micafungin in the treatment of experimental Candida albicans keratitis in rabbits compared with fluconazole.

METHODS

In 1 eye of 24 New Zealand white rabbits, C. albicans (5 x 10 yeast cells) was inoculated in the corneal stroma. The animals were randomly assigned to 3 groups and received subconjunctival injection of 0.5 mL of 0.1% micafungin, 0.2% fluconazole, or physiologic saline once a day for 3 weeks. The eyes were examined slit-lamp biomicroscopically and histopathologically. The clinical course of fungal keratitis was compared among the 3 groups. In another 36 rabbits, a microbiological examination was performed using a quantitative isolate recovery technique, and the numbers of colony-forming units were compared among groups.

RESULTS

The clinical scores were significantly lower in the micafungin group than in the other 2 groups throughout the study period (P < 0.0001 approximately P = 0.0027, Bonferroni multiple comparison). The fluconazole group showed significantly lower clinical scores than the saline group on day 18 (P = 0.0343). At the end of the study period, there were significant differences between the saline and micafungin groups (P < 0.0001), the saline and fluconazole groups (P = 0.0072), and the fluconazole and micafungin groups (P = 0.0013). Histopathologically, similar results were obtained. Moreover, the results of the microbiological examination nearly matched the clinical and histopathologic findings.

CONCLUSIONS

Subconjunctival administration of micafungin was effective in the treatment of experimental Candida keratitis. Local application of micafungin to the eye would be a feasible treatment option for clinical fungal keratitis.

Trends in Microbial Keratitis in Japan

PURPOSE

To identify microbiologic characteristics of infectious keratitis and predisposing factors.

METHODS

The microorganisms isolated from patients with infectious corneal ulcers during the 5 years between January 1999 and December 2003 were retrospectively examined. Herpetic and other viral infections were excluded from this study. Patient age, sex, risk factors, and isolated organisms were collected.

RESULTS

In 123 eyes of 122 patients, organisms were isolated from 72 (58.5%) eyes. In total, 99 different organisms were isolated. Among these, 77 (77.8%) were gram-positive bacteria; 18 (18.2%) were gram-negative bacteria; six (6.1%) were fungi; and one (1.0%) was acanthamoeba. Contact lens wear was the main risk factor (54.5%), and ocular surface disease and previous ocular surgery were present in 20.5% and 13.1% of cases, respectively. Posttreatment visual acuity was significantly improved by pretreatment in culture-positive groups treated according to the antibiotic susceptibilities (Wilcoxon t test, P<0.01).

CONCLUSIONS

The results are changing to those reported by other countries and generations. Contact lens wear is the most important risk factor in Japan. The results of isolation and culture are essential for improving the cure rate.

In vivo confocal microscopy in fungal keratitis

BACKGROUND

Fungal keratitis is a major blinding eye disease found throughout the world, particularly in developing countries. Given the recent increase in Fusarium keratitis infections in contact lens wearers owing to contact lens solutions, a warning was recently issued by the Food and Drug Administration, making it a public health concern in developed countries.

OBJECTIVE

To show the advantages of in vivo confocal microscopy imaging using the Heidelberg Retina Tomograph II-Rostock Cornea Module (HRTII-RCM) in the early diagnosis of fungal keratitis.

METHODS

HRTII-RCM confocal microscopy was performed on five patients presenting with fungal keratitis and on three donor corneas contaminated with Fusarium solani, Aspergillus fumigatus and Candida albicans.

RESULTS

Direct microscopic evaluation of corneal smears and culture revealed the presence of F solani in four cases and C albicans in one case. HRTII-RCM examination of the infected patients and contaminated donor corneas revealed numerous high-contrast elements resembling Fusarium, Aspergillus hyphae or Candida pseudofilaments in the anterior stroma.

CONCLUSION

HRTII-RCM in vivo confocal microscopy is a new, non-invasive and rapid technique for the early diagnosis of fungal keratitis, showing high-resolution images resembling fungal structures in the early phase of the disease.

Spectrum of Fungal Keratitis in North China

PURPOSE

To report the epidemiological features, laboratory findings, and treatment outcomes in patients with fungal keratitis in north China.

DESIGN

Retrospective hospital-based study.

PARTICIPANTS

A total of 654 patients diagnosed with fungal keratitis at the Shandong Eye Institute from January 1999 to December 2004.

METHODS

The medical records of 654 inpatients (654 eyes) with fungal keratitis were reviewed retrospectively for demographic features, risk factors, seasonal variation, clinical characteristics, laboratory findings, and treatment strategy.

MAIN OUTCOME MEASURES

Patient history, ocular examination findings by slit-lamp biomicroscopy, laboratory findings from direct smear examination and fungal culture, and treatment protocol.

RESULTS

Fungal keratitis constituted 61.9% of cases of severe infective keratitis among the inpatients at the Shandong Eye Institute during the 6 years. Males (60.6%) were more likely to be affected by fungal keratitis than females (39.4%). Almost one third of the patients (203) were middle aged (41-50 years old). Corneal trauma (51.4%), especially injury from plants (25.7% in all patients), was the most commonly associated risk factor. The incidence of fungal keratitis was higher in harvest seasons, including summer and autumn. An increasing tendency of incidence was noted in more recent years. Direct microscopic examination of the corneal scraping samples stained with potassium hydroxide showed positivity in 88.7% of the eyes. The fungal isolates were of Fusarium species in 437 eyes (73.3%) and Aspergillus species in 72 eyes (12.1%). Surgical interventions were performed in 604 eyes (92.4%), including therapeutic penetrating keratoplasty in 399 eyes (66.0%) and therapeutic lamellar keratoplasty (LK) in 177 eyes (29.3%). Globe integrity was preserved in 626 eyes (95.7%).

CONCLUSIONS

With Fusarium species being the most commonly isolated pathogens, fungal keratitis is the leading cause of severe infective corneal ulcers in north China. Direct microscopic examination with potassium hydroxide wet mounts proves to be a rapid, simple, inexpensive diagnostic means. Corneal transplantation continues to be the most effective approach for the treatment of severe fungal keratitis. Early surgery, especially LK, can be considered if aggressive topical therapy does not achieve early disease control.

Problème diagnostique et thérapeutique de la kératite mycosique en zone intertropicale. Intérêt de l’usage local de la polividone iodée

Fungal infection is rarely investigated in keratitis. The authors report five cases of fungal keratitis observed at the le Dantec University Teaching Hospital of Dakar, Senegal, involving two males and three females. Diagnosis was made by examination of smears and cultures of corneal scrapings revealing Candida albicans isolated in four patients and Acremonium strictium in another after 2 or 12 weeks of treatment with antibiotics, antivirals, or steroids. Povidone iodine 2.3% concentrated eye drop was used alone or with an azole for 4 a mean of weeks. All patients presented corneal scars. Fungal keratitis must be considered in presence of torpid corneal ulcer and corneal scraping must be systematically done. Topical povidone iodine alone or associated with azole may be an alternative fungal keratitis treatment in intertropical areas.